My ads vary by day... for the longest I had one for plentyoffish.com (a dating site, I think?!), and right now it is for a website building tool. Lately it has been for overstock.com and some website where there are dogs on the ad looking like they've stuck their head out the window. No idea.
At what point can we ask for certain ads to be removed? Do they have to be nasty? Or things like that designer dog forum... that somewhat compete with PF?