How are you going to find a guy who never watches porn though? If you ask them up front, most likely they'll lie to you about it. Most guys have at times watched something, doesn't have to be anything extreme, but you know, through a spell of being single 6 months +, they aren't going to be sitting around keeping their hands on the desk/over the blanket, waiting til a nice woman comes round.
I do think what you described re your ex is quite extreme and if I'd find out my partner was like that, I couldn't be with them, end of. That's more an obsession than casual watching/ scratching an itch and realising on-screen isn't realistic.
I think what's more effective is having an open conversation with a partner about sex and porn and take away some of the shame around it. I like that my partner was able to tell me what he watches and why, what he watched as a young lad etc, what I watched... It was all quite humorous and relaxed and put us both more at ease.
With my ex I genuinely thought he didn't watch anything/ wasn't interested for a long time, I always knew where he was and what he was doing. He had a respectful attitude to women, was maybe a bit dull at times sexually, just generally displayed less interest in women/sex half the time than most guys I know. Once, in a fight, he threw in my face that he watched porn when I was unavailable, as though that should shock me.
I really think they all do at times, even the 'really good ones'. I'd be a bit suspicious about a man if they weren't even a bit curious once every few years.