Just don't hire anyone that basically has a bad reputation for going around "forum hopping". Try to find someone that has a passion for games. People that love games and like to tell about them would be the great person for the job. Before hiring a reviewer, ask to see any previous reviews that they may have.
Post on gaming forums to ask. Most likely you will have a better chance at finding someone there than any other forum.
Just a couple mods and I make quality reviews and interviews, and our members will always want to get involved.
And those that do, the members that is, would be the "future staff" of my site down the road.
I never hire staff, everyone on my team asked for their positions, that and I know each of them anywhere from a few weeks to 4 years with one member.
Game reviewers are the toughest to find, let alone quality reviewers. Almost all gaming forums have a review section, but they're almost always either dead, or the least active. They're a tough sell to get members to contribute.