I am working on a project now where somebody has ported their site from a static environment (non-CMS one) to a WordPress site, but some of their styling is not showing up now. After banging my head against the wall for a while trying to figure it out I discovered that it appears that WordPress is removing any element that uses legacy attributes such as:

Code HTML4Strict:
<hr size="2" noshade="noshade" />

and just not showing it at all. Maybe this isn't exactly the problem (I'm still working on figuring this out) but I think it's at least pretty close to being the problem.

Has anyone encountered this before? Is there a way to get WordPress to cooperate?

This is time-sensitive so that I can't (right now anyways) convert all the old-style code to CSS-friendly code, although that may come later.