Looking at Bike Forums as a "business," they have to make money somehow. It costs money to run. Advertisers pay BF ownership to put ads up, free members and guests see the ads- possibly getting them to go to the advertiser's site; For all I know BF gets money anytime an ad is clicked or a customer is redirected. Suscribing members pay to use the forum and as a benefit- do not see the ads. Bike Forums gets their money.

The ad companies that make the ads want their customers to get their message across- so you get overbearing ads that take over your computer and use up processor and memory allocations to make the ad impossible to ignore. Advertisers want their return on the investment of advertising.

Whoever on BF or Internet Brands or whoever vets the ads can miss stuff like hijacking software in the ads. It shouldn't be an issue with reputable advertisers and ad companies- but you never know... I guess...