I'm not sure how many of these comments are true.
Urinary catheters can be used during surgery, but it depends on where the surgery is being done, then length of the procedure, and the type of anesthesia being used.
Regarding temperature probes, they may use a rectal probe, they may use a probe built-in to the foley, they may just tape a skin probe to you. I've seen all three done, and again it depends on the procedure, the standards of the institution, etc.
For example, if you're going to have a catheter placed for the surgery, they might as well use one with a probe and avoid having to place another one. BUT, the foleys with the temperature probe are rather expensive (medical ripoff level), so they very well might use a rectal or skin probe. If they are worried about you going into hypothermia during a long procedure with a lot of IV fluids, I would expect them to place a rectal probe. If it is a shorter procedure, they would just tape a skin probe to you...faster and easier for everyone.
The rectal probes they use on the anesthesia carts can also be placed in the esophagus, and often are. Don't worry, those are disposable probes.
I went in for a dental surgery procedure under IV anesthesia and was shocked when I woke up that they had taped my eyes shut and coated them with lacrilube. I then asked--and had it confirmed--that they had intubated me. I was quite shocked, I had not expected that at all. They waited until the IV sedation took hold, then intubated me.
I've seen hundreds of procedures, with the patients nude and sedated and nobody was ever anything but professional. If they were not, we would have raked them over the coals.
I saw one resident once make a comment about how attractive a patient was. We were all shocked and everyone just stared at him; you turn that sort of thing off when you get into the room.
I don't know what happened to him, he was transferred out during his first year. Rumor was that he had other issues and was helped to go away.