Quoted from robin:As for hiding ads from certain users: currently, that is not possible. The plan is to link it to the ignore feature so in the future you could ignore a user to no longer see his ads.
That would be great to see!
Similar to OP's issue, my search criteria yields a vendor who never comes on the forums and just posts each and every NIB title every week in the Market at retail/inflated prices. Since those are always posted over and over again by that vendor, and because I'm never going to buy a NIB game like that, typically half of the results I scroll through are of no use. I'd love to block that vendor so their results never come up. Looking forward to that feature! 
