There are bag checks at the Forest Hills T stop most mornings. Usually about five police officers are doing the checks, mainly standing around a single table. I've never been stopped, but I find large officers pretty intimidating nonetheless.
In fact, I've actually never seen a white person stopped. The only individuals I've seen checked are African American males.
This stood out to me today as a school-aged teenager was trying to go through the turnstile and a policeman literally had his hand on his chest stopping him and pulling him aside for a check. Even if they knew something I didn't about this person, NOT COOL.