They rarely let us down. If it seems too good to be true, it may very well be. If you feel unsafe for any reason, walk away. Work on overcoming shame. Your own willingness to endanger yourself and others can also be another indicator of how shameful you may feel to be enjoying yourself in a toilet stall or public park.
Shame is very hard to overcome, but it can be done.
Sex is a life-affirming, healthy part of life. If you find your favorite tearoom stall is busy, don't decide to simply hang out in the common area of the toilet. Walk around the mall or campus a bit and come back later. If you arrive and someone else is already there waiting but after a while it is clear that person is not interested, give up your stall and leave. Don't take it personally, you may not be his type.