> Then there are just ridiculous pronunciations. "Supposed" pronounced as "spost," "comfortable" pronounced as "comfterble" (which was a reader poll a while back), and "clothes" pronounced as "close" are the ones I can think of specifically.

Eeep. That's two out of three for me, and three out of three if I'm a in hurry. I usually say "supposed to", but sometimes return to my childhood "sposta" when speaking quickly. "Comfortable" I simply grew up hearing in the "comfterble" form, and can't really remember hearing otherwise. It just doesn't sound right in the other form when coming out of my mouth. As for "clothes", I find it difficult to pronounce the "s" immediately after the "th", though I'm aware that I should at least try to amend this problem.

Burger"What about 'laboratory'? When does mispronunciation become simple regional variation?"King