If you only use the free service they will not be able to scam you.
Two scenarios:
1. A free service that doesn't work, will make those desperate newbies to try the paid service instead (which in turn, will be scammed).
2. Their (those newbies) transactions might received confirmations (especially now, since transaction fees and backlog of unconfirmed transactions is a lot lesser) normally (being mined by an actual pool) and yet they tip him for something he didn't do in the first place (and that's to accelerate those transactions).
No one is forced to pay for our work!
We use all free tools we know and pool accounts we have avaliable to help, nothing more. We got help in the past ourself, so we try to give a little back.
If you do not trust us do not use our service.