Gigs could be hidden from buyers with certain Low feedback, or payment issues, or high cancelation rates.
Being able to limit gigs to those within our own country, or those who know your language fluently would be nice too.
We've all dealt with the buyer who barely speaks our language and will then end up misunderstanding each other, or the whole gig it self.
Fiverr could copy the process from eBay's buyer restrictions, and exceptions list.
And of course the whole thing could be Optional to the seller.
Think how long it took EBay to develop those things. Fiverr is only 3 years old