Luck! Luck! Luck! is all you need.
Emblems and such may make you think twice Etc but from there I then go to his squad, check all of his players not in the first eleven, check their games played, three or four with no games but good quality suggests he has been very active that day.
Players ending 4/9 ratings and with SA would also suggest he has spent heavy that day in tokens, that's if you know how much activity there is on this type of player on your server.
Used this method yesterday, went in at the last second against a big squad builder, secured the player with two tokens, the other guy had bought five players that day and had two players in his squad already for that position, one slightly higher quality on one lower, guess my fancy emblem made his think twice or he had burnt all his tokens earlier and didn't want to risk what he had left.