End Results

How does this arms race affect spammers?

the standard HELO function with the standard headers that comes with [spamware X] scores very high on SpamAssassin etc and therefore the mailings are subsequently blocked and filtered... people using [X] need to use unique custom headers

Finally, those "special" ways of masking the emails ... If anything, SpamAssassin will  give you MORE points for such things, rather than let your message get through.

Key is to randomize EVERYTHING, this is not simple like it used to be it is more of an art now