What is their background? Will they try to inflict their agenda on the person being searched for? Have they conducted searches before? Do they have trained professionals that they can call upon for advice? Do they have a neutral position in the search? Are they affiliated with anyone that had anything to do with the adoption? Is it clear who they are really working for? 

Who you choose to conduct your search and make the initial contact can make or break your reunion. A large proportion of the searches will turn out just fine with no problems. Those are not the ones that you need to be concerned about. The ones that are on the fence about what to do, the ones that are easily agitated, the ones that feel they are being intruded upon are the ones that you need to worry about.