Trust your gut
Most of the time, people who believe they're being cheated on end up being correct. "You know, they’ve been married to someone for a while -- they know their habits, they can say, ‘Now he’s dressing nicer all the time,’ or ‘He didn’t wear cologne, now he wears cologne.’ You know, the obvious, apparent changes,” McKeever says.
Women are far more intuitive about this kind of stuff, too. "It’s pretty much known in the private eye business that if a woman hires you, probably 90% of the time or more, she’s not wasting her money. If a man hires you, probably 75% of the time or more, he is wasting his money."