I don't think it has anything to do with this forum. Some time ago, at the last place I worked, I went on-line to show a co-worker some gloves at Motorcycle Superstore. Forever after I would get pop-up ads from them whenever I put my work computer on the web. A few months ago I had my GMC truck serviced at a local dealership, and gave them my email address so they could communicate with me. Now, every time I visit the gm-trucks.com forum, I get ads for that dealership. A couple of months ago I was looking for repair info for my Stihl chainsaw, now when I access my gmail account, I have ads for Stihl equipment.
Big Brother, Little Sister, and all their cousins ARE watching and they ARE searching keywords and phrases. It is part of how the interweb works, and everything is monitored and cross-referenced.
2007 ABS Wee-Strom "The Silver Surfer"
2003 Kawasaki Concours "Mabel, the Flying Kaw"