Apparently through the use of some terrible keywords in your emails you can get rid of them. GoogleAds which reads your email and looks for keywords to generate ads from will not show ads with bad keywords as a matter of taste, a filter for taste as you would. However if you’re really adamant on getting rid of Ads, there are easier alternatives using firefox addons like AdBlock and such.

http://lifehacker.com/5330642/massacre-gmail-ads-with-these-two-sentences-and-some-tragic-words

Try it out!