Confluence continues to add color and font designations into the wiki markup even though I do not specify it in the WYSIWYG rich text editor view of my content, and I explicitly delete it from the wiki markup before saving the page. It continues to add bold font designations and color tags anyway, ignoring my explicit intent. See examples below:
<b>Contents</b>
<font color="#333333">Novice and experienced developers</font>

This annoys me and also affects the accessibility of my web pages.

There are several web accessibility checker tools you could use to test Confluence conventions, to check for and eliminate these behaviors. For example, see http://achecker.ca/checker/index.php

The output shows, for example:
– Check 116: b (bold) element used. Repair: Replace your b (bold) elements with em or strong.
– Check 177: font used. Repair: Remove the font element from the document.