There are older guys who use the gym I used to go to who are comfy being naked in the changeroom, and would even sit barebum on the change benches, this I found a bit odd, however shaving your FACE at the gym wouldn't be odd to me, you've just bad your morning shower etc. Wouldn't fancy using a straight there though it would be to easy to get knocked at the wrong moment. Shaving anything else would be off putting, but on the other hand full length mirrors could be useful :-)