This happened in early 2000 in the men's room on the A-level of Doherty Hall at Carnegie Mellon University. It was reported that at least ten gay men between the ages of 17 and 60 engaged in sex anonymously through the use of glory holes in the toilet stall walls. In the months since, many signs reading "CAMPUS POLICE ACTIVELY PATROL THIS AREA!" have been placed in the vicinity of this washroom.
After the incident happened and was reported in the campus newspaper The Tartan, many people on the campus bboards were concerned about it. After all, sex of any kind at CMU is always a cause for alarm. Two other spots on campus were named on a web site for gay sex: a washroom in Baker Hall was the target of a similar sting some years ago, and the sauna in the men's locker room of the University Center apparently is also a hotspot. My roommate at the time claimed he was nearly seduced by a guy in said sauna, prompting him to make a run for the door to get his clothes back on.
Personally, I would rather not see anyone, gay or straight, having sex in a public lavatory. I just go in there to relieve myself, not be exposed to a peep show.
One user wrote to say "Bathrooms in college libraries are a popular spot as well. I know that the ones at University of Arizona and UVA were used for this purpose, probably there are others. (And no, I had nothing to do with it)"