Can't verify ThaiFriendly. Never used it.
Grindr is well used in BKK and Pattaya.
10k is way, way too high. Avoid these, clearly trying to rip you off.
If anyone asks, this isn't your first time in Bangkok
Some folk are very trusting and don't think of this: Keep your valuables in the room safe when you invite someone to join you at your hotel, don't leave your phone and wallet on the side when you go to shower with them in the room - especially so if they're from Grindr, TF.
Enjoy and have fun!