Add number of answers deleted

In the meantime, there's a userscript that will do something similar. The link provided on StackApps is dead, but I found the code on userscripts-mirror.org, and modified it (below) to make it work on all Stack Exchange sites.

You need to have a userscript manager (like Greasemonkey or Tampermonkey) to use this script. It doesn't look like it's been updated for a while, but I'm using it on SciFi&Fantasy and it seems to work (tested on How was Ronan able to handle the Infinity stone without being destroyed?, which has 11 deleted answers):

This script has the added benefit of hiding deleted posts if you don't want to see them, or hiding just their content if you don't want all the deleted noise to distract you.

Updated Code

// ==UserScript==
// @name         StackOverflow - Deleted Answer Manager
// @namespace    http://hishills.com
// @version      1.0
// @description  This script allows you to collapse or hide deleted answers on StackOverflow
// @match       *://*.askubuntu.com/questions/*
// @match       *://*.mathoverflow.net/questions/*
// @match       *://*.serverfault.com/questions/*
// @match       *://*.stackapps.com/questions/*
// @match       *://*.stackexchange.com/questions/*
// @match       *://*.stackoverflow.com/questions/*
// @match       *://*.superuser.com/questions/*
// @copyright    2012, James Hill
// @updateURL    http://userscripts.org/scripts/source/133048.user.js
// ==/UserScript==

function main() {
    var relevantAnswerCount = $("#answers").find(".answer").not(".deleted-answer").length;
    var $deletedAnswers = $("#answers").find(".deleted-answer");

    // Modify the page only if deleted answer(s) exist
    if($deletedAnswers.length > 0) {
        /***********************************************************************************************************************************************/
        // Deleted answer content toggle
        /***********************************************************************************************************************************************/

        // Add show deleted answer content
        var toggleText;
        if(localStorage.getItem("dam-ShowAnswerContentByDefault") != null) {
            toggleText = localStorage.getItem("dam-ShowAnswerContentByDefault") == "show" ? "hide content" : "show content";
        }
        $(".deleted-answer .post-menu").append('<span class="lsep">|</span><a href="#" class="toggleDeletedAnswerContent">' + toggleText + '</a>');

        // Show/Hide content click handler
        $(".toggleDeletedAnswerContent").on("click", function(e) {
            // Cache this
            $this = $(this);

            // Toggle visibility
            $this.closest(".deleted-answer").find(".post-text").toggleClass("deletedAnswerContentHidden");

            // Toggle text
            var aHtml = $this.html()
            $this.html(aHtml == "show content" ? "hide content" : "show content");

            // Prevent default action
            e.preventDefault();
        });

        /***********************************************************************************************************************************************/
        // Deleted answer visibility toggle
        /***********************************************************************************************************************************************/

        // Change answers sub-header
        var relevantAnswerText = relevantAnswerCount + " Relevant " + ((relevantAnswerCount == 1) ?  "Answer" : "Answers");
        var deletedAnswerText = "<a href='#' id='toggleDeletedAnswerVisibility' title='Toggle deleted answer visibility'>" + $deletedAnswers.length + " Deleted " + (($deletedAnswers.length == 1) ?  "Answer" : "Answers") + "</a>";
        $(".answers-subheader h2").html(relevantAnswerText + ", " + deletedAnswerText);

        $("#toggleDeletedAnswerVisibility").on("click", function(e) {
            // Toggle deleted answer visibility
            $deletedAnswers.toggleClass("deleted-hidden").toggle();

            // Gray out link
            $(this).toggleClass("deletedAnswerHidden");

            // Prevent default action
            e.preventDefault();
        });

        /***********************************************************************************************************************************************/
        // Preferences
        /***********************************************************************************************************************************************/

        // Insert prefs text
        $("<div id='preferencesText'>&nbsp;&nbsp;&nbsp;<a href='#'>(prefs)</a></div>").insertAfter(".answers-subheader h2");

        // Insert prefs div
        $("#preferencesText").append("<div id='preferencesDiv'> \
                                        <b>Deleted Answer Preferences</b><br /><br /> \
                                        By default, <select id='ddlShowAnswersByDefault'><option value='hide' selected='selected'>hide</option><option value='show'>show</option></select> deleted answers. <br /> \
                                        By default, <select id='ddlShowAnswerContentByDefault'><option value='hide'>hide</option><option value='show' selected='selected'>show</option></select> deleted answer content. <br /><br /> \
                                        <input type='button' id='btnSaveDeletedAnswerPreferences' value='Save Preferences'> \
                                      </div>");

        $("#preferencesText a").on("click", function(e) {
            $("#preferencesDiv").slideToggle();

            // Prevent default action
            e.preventDefault();
        });

        $("#btnSaveDeletedAnswerPreferences").on("click", function() {
            // Close prefs div
            $(this).parent().slideToggle();

            // Persist prefs using local storage
            localStorage.setItem("dam-ShowAnswersByDefault", $("#ddlShowAnswersByDefault").val());
            localStorage.setItem("dam-ShowAnswerContentByDefault", $("#ddlShowAnswerContentByDefault").val());
        });

        /***********************************************************************************************************************************************/
        // Honor Preferences
        /***********************************************************************************************************************************************/

        // If prefs exist, honor them
        if(localStorage.getItem("dam-ShowAnswersByDefault") != null &&
           localStorage.getItem("dam-ShowAnswerContentByDefault") != null) {
            // Set drop down values
            $("#ddlShowAnswersByDefault option:selected").removeAttr("selected").parent().find("option[value='" + localStorage.getItem("dam-ShowAnswersByDefault") + "']").attr("selected", "selected");
            $("#ddlShowAnswerContentByDefault option:selected").removeAttr("selected").parent().find("option[value='" + localStorage.getItem("dam-ShowAnswerContentByDefault") + "']").attr("selected", "selected");

            // Honor prefs
            if(localStorage.getItem("dam-ShowAnswersByDefault") == "hide")
                $("#toggleDeletedAnswerVisibility").trigger("click");

            if(localStorage.getItem("dam-ShowAnswerContentByDefault") == "hide")
                $(".deleted-answer .post-text").addClass("deletedAnswerContentHidden");
        }
    }
}

// Add script element to head of document so that SO's existing jQuery can be used
function addJsScriptBlock (funcToRun) {
    // Create script node
    var scriptNode = document.createElement('script');
    scriptNode.type = "text/javascript";
    scriptNode.textContent = '(' + funcToRun.toString() + ')()';

    // Append script node to head
    var targ = document.getElementsByTagName('head')[0] || document.body || document.documentElement;
    targ.appendChild(scriptNode);
}

// Add style element
function addCssBlock (css) {
    // Create script node
    var styleNode = document.createElement('style');
    styleNode.type = "text/css";

    // Add CSS
    styleNode.appendChild(document.createTextNode(css));

    // Append script node to head
    var targ = document.getElementsByTagName('head')[0] || document.body || document.documentElement;
    targ.appendChild(styleNode);
}

// Add CSS
var css = ".deletedAnswerHidden { color: LightGray !important; } \
            #preferencesText { display:inline-block; margin-top:10px; } \
            #preferencesDiv { display:none; float:left; position:absolute; margin-left:12px; margin-top:15px; border:1px solid Black; padding:5px; background-color:White } \
            .deletedAnswerContentHidden { display:none; }";
addCssBlock(css);

// Add JS
addJsScriptBlock (main);