I've had that happen too but its a rare occurrence. Usually its someone that doesn't even think to look if someone else is using it.
I don't use wrist wraps or a belt so I have limited items to set on or around the bench but fuck, there's chalk all over the bar, a bag of chalk on the bench and my gym card. They usually tuck tail and run when they realize its my bench.
Speaking of people not making any effort or perhaps just being clueless (this case is clueless)...I was laying back on the bench, hands on the bar, about to get into position when someone to my right asked, "hey, are you using that?" I stared at him for about 20 sec and asked him if he was serious. When all he could do was give me a blank stare back, I immediately started laughing, shaking my head, and telling him what an idiot he was as I got back under the bar.
Lol, you should have told him you were posing for Playgirl magazine and he was interrupting your photo shoot.
You want to talk about clueless? There's this guy at my gym who is always good for some laughs and tonight was no different. After his usually deadlifts with a super rounded back looking like the hunchback of notre dame he picked up a PVC pipe to do curls with....an empty 1in PVC pipe. He did a few sets with it and then, here's the kicker, he proceeds to do what I can only describe as single arm dumbell AIR curls. Why do I call them air curls? Well bc there was nothing in his hands as he did a curl movement. Absolutely nothing. He just did the curl motion with nothing in his hands lol. I think he was trying for that mind muscle connection or whatever ppl call it. I ended up dropping a 60lb DB on my toes and got reprimanded for shouting out FUCKKKKKKKKKKK but it was worth the laughs hahaha