Priestly Endeavors has a post On hiring for guild needs. It’s definitely something to think about. In essence his post seems to boil down to ask for what you need, not for a specific spec. This seems to me to be especially true with the Burning Crusade where a lot of hybrids have really come into their own. For example, rather than recruiting a prot warrior, recruit a tank; rather than recruiting a survival hunter, recruit a skilled crowd controller. Run an instance or two with them filling the expected role and if they can’t perform it, recruit someone else.
Pre-Burning Crusade I ran a lot with a paladin who tanked and did an amazing job. It drove him nuts that the raid leader would not let him tank in raids, even though he had demonstrated the necessary skill. Despite his being improperly specced and the wrong class I much preferred doing runs with him tanking rather than doing runs with most of the warriors in guild.