Best thing to do is just flat out ask him about it. No sense in trying to see what he looks at. Just ask him! If that's what he wants to look at, he has the right to do it. If you don't want him to see these things then confront him about it and ask him why or to please stop.
My husband has a Alcatel one-touch phone, and I think he uses his incognito tab to look up porn. Is there a way to stop it or see what he's looking up?
Well, how do you know it's porn if you can't see it? I have to say, when I got my phone, I pressed the "incognito" put on and for the life of me, I can't figure out how to take it off.