no different from him using his fingers in the same erotic way. the size would be of interest and so long as he can take it too, lol what fun.
Whats wrong with a man exploring his ass?
I think more men should be open to exploring what fun they can have with their ass, before writing it off completely. You never know, until you try.
Is the man using the butt plug on himself or on his wife?
Personally I think its hot ;)
If that is what he wants and enjoys, I'm happy that he's happy.