which while i understand and concur with your hatred of unsolicited sales emails, is the point of them :) much the same as ads on TV, i don't want to see then but if im going to be forced to, at least don't make them offend my eyes,
(not much can be said for badly designed marketing messages though)
If communication that you actually wanted to receive was sent in plain text then you could easily filter HTML email and be rid of it. Spammers aren't going to stop sending HTML mail because it is so useful for what they do, but no one else needs it.
This is incorrect. Just because spammers use HTML email doesn't mean HTML email is evil.
To give a very practical example, I sign up for newsletters from FontShop so I can be updated about new fonts. The email includes images to show how the fonts look. The utility of these emails would be drastically reduced if they were to use plain text.
(not much can be said for badly designed marketing messages though)