When I use my phone, I don't have the info of the players team as his stats too.
So, the signs I use are
- the price (must be near the numbers of the list I have)
- no premium jersey
- the hour (must be 04.00-06.00 GMT) . There are no original nordgens except this hour (but not impossible to find a fast trainer from other teams/managers who are selling them for some reasons - injury, bad performance,finance problems).
In that case, I avoid to spend much token for the player, so if he isn't fast trainer or excellent performer, I sell him back.

Those signs are also if some manager using a bot team name.