Evading Spam Filters with Spam?

In order to evade Bayesian filters, spammers add lorem to their mails so that they look legitimate. This is in addition to the odd punctuation or misspellings of words that will ordinarily show up in the Bayesian filter's vocabulary blacklists.

Do you think the spam will ever get to a point of maturity that we have to add spam vocabulary to our legitimate emails just to get them through the spam filters? Meaning, will the spammers ever stop making it so obvious the type of product they're advertising that those words get removed from the filters, meaning legitimate emails would need to have enough of those just to get by the filters?

Man I wish more people would adopt and pay attention to S/MIME or PGP signatures. Obviously, spammers can use those signatures as well, but at least then I can have my email client check who the signature is from for me. Rats! There are always trojans to send the emails out and fill in the passphrase boxes, too.