I don't think I am a tough guy, but I seem to be the only person around who can put animals out of their misery. And glue traps create a whole lot of misery.
A glue trap can be a shallow tray with thick glue or an over-sized sheet of scotch tape. Well, that describes the two traps I have been involved with. Sometimes there is bait in the middle of the trap.
If the user is prepared and has actually read the frickin' instructions, the traps might not be that bad. Apparently (according to Wikipedia), cooking or baby oil will allow the animal to escape the glue. This is useful in a rural area but not so much in a location where the animal will have to be killed anyway.
Seven years ago, I lived and worked for a nightmare company in a beautiful location in rural Kyonggi-do. At one point, there was a problem with mice, so staff set up glue traps - but not very well, as one of the first catches was a little bird. The bird, in terror, tore most of a wing off while staff watched. I had not heard that oil could release the bird, and the people who set the trap weren't prepared; there was none on site. Finally, I took the bird and twisted it's head like I was winding a top. Honestly, I almost cried, but was satisfied the job was done. One jerk co-worker almost got punched for calling me a sadist. He had had no better suggestions in the fifteen minutes previous.
Today, at work, a rat had made it's way into the ESL offices. Again, staff had set up a few glue traps. Now, I approve of live traps if there is a plan to release the critter, but who releases rats? Who buys a glue trap and doesn't prepare to release the critter afterwards?
Anyway, the rat was caught and in it's struggles, nearly tore a leg out of it's socket (I'm not a doctor but I'm repeating what a staff member told me). I was in a meeting and later found the rat, on the floor near a garbage can in an out-of-the-way room. The rat had crapped everywhere - and that too was glued in place and it was clearly in a bad way.
After asking about their plans for it - none, I guess they hoped it would die quietly out there - I stomped on it, ending it's misery.
If you plan to trap an animal, also plan how you will dispose of the animal later. Use a non-leathal trap only if you want to release it afterward. If you plan to kill the animal, get a leathal trap: don't screw around.
These guys at Helping Animals don't care for glue traps either.