Is it normal that i look at women's shoes all the time?

I am a guy in his mid 20s. I constantly look at women's shoes. Like on or off a woman. It's almost like an obsessive checking habit, I have to look at a woman's shoes to see if they are nice. Problem is, if they are sexy ones, I find it hard not to look, and particularly hard not to think about looking at them.
Another quirk is that there are particular ones that are a 'yes' and ones that are a 'no' pointy shoes or trainers are a no, whereas high boots, heels, that kind of thing is a definite yes. Same rules apply to shoes in shops too. Does anyone else do this?