NB is your home away from HOME.
I hate in DP is the "free review copy" in exchange of an honest review. The fact that service providers are working their butt in every service that they are providing while other people take advantage of them being "new" or have few "post counts". And in the end, they will say "service recommended" "will use the service again" but in reality they won't even use the service again.
To avoid scams, just ask the service provider to pay after the work is done to establish trust which is likely better than asking for a free review copy.