It true the sites can tell, but only if they are looking for it. If you ever think one is at your table pm security so they can check for it.
There are patterns such a when and how they bet and the cards they hold or show up on the board. You watch and note you might pick up on which ones they are but it takes time.
Most bolts don't do tourneys for the simple fact of downsize, the program is a set one so most are not able to reprogram them that fast to be able to handle tourney play.