I would never go for a hooker or another woman while married. For one, hookers are nasty. Another thing, hookers aren't free, and I'm not rich. For a third thing, I get pussy for free at home.
In the Middle-Ages it was even condoned by the Church and brothels were commonplace in European towns...
So why make such a big fuss nowadays? Thought we pride ourselves of living in a much more open society...
Guy has a need - guy gets a service from a prostitute - problem solved! It's not cheating for love, it's business, no big harm done.
Just make sure you stay safe, and always wear a rubber. For your sake, the sake of the prostitue, and your wife.
In the hypothetical scenario that I'm both straght and married, I doubt it would bother me much if my husband paid a hooker sometimes. If I were married to me, I'd cheat on me too. And as long as it stays physical and business-like, I've got no problem with it. I'd have a bigger problem with them having a crush on someone, even if it never went anywhere. To me, emotional fidelity matters more than physical fidelity.