As someone who gets a lot of newsletters from idiots who still think they own the GMail address I've had for 13 years, I'm always afraid marking things as Spam will hurt my experience more than the spammers -- eg, I'm worried it'll lower my account's spam threshold and cause more false positives in my spam folder (which i never, ever check.. and on the rare occasion I do, I occasionally notice I've been 'missing' a newsletter I should have been getting for years).

Any comments as to how this works? I've happily used the spam button on many occasions, but I'm always a little gunshy.