I can absolutely understand why you wouldn't be keen on your husband following a load of random bikini women on Instagram and liking all their pictures - I wouldn't be delighted either, just because it's all a bit obvious and naff.
But unless they are completely asexual, men do find beautiful women (whatever beautiful means to them) attractive, so I guarantee you that if your husband does see a photo of a beautiful 25-year-old in her undies, he definitely doesn't think 'How revolting, she is only a few years older than my daughter. I am repulsed'. And that doesn't make him a pervert - quite the opposite in fact. A pervert is someone who is sexually aroused by something that deviates from the norm. A man who finds a woman in a bikini attractive is, in fact, absolutely the norm.
It is also completely normal and human for women to find men attractive. Again, not perverted. Just biology, really.
And I wouldn't go out of my way to Google pictures of men I found attractive.
Fair enough. But if you do happen to see one without actively searching, though, what's your reaction? For example, if there's an actor you find attractive, and you were flicking through a magazine in the doctor's waiting room and there was a picture of said actor, do you close the magazine in horror at the sin of seeing the face of a good-looking man or feel embarrassed that you might have accidentally been a pervert by thinking 'Goodness, he's handsome'?
I guess what I'm trying to figure out is whether you think it's only liking/following good-looking celebrities that's the problem, or whether you're saying that simply finding someone hot, without actively looking out for them, is also unacceptable and perverted.