Private Investigator reveals one common thing that gives all cheating men away

It can be heartbreaking at best and downright life-shattering at the worst of times when a long-term relationship runs its course.

There are a whole bunch of reasons why a relationship may not work out in the end, but it's safe to say the whole healing and closure process becomes a whole lot harder when infidelity has had something to do with the split.

It can also be extremely distressing when you find out the person you loved more than anything in the world let you down and, in many cases, the way in which you're alerted to this heart-shattering reality can be just as emotionally arduous.

There's apparently one major habit men do when they're cheating. (Peter Dazeley/Getty Images)

Stumbling across some flirtatious emails is one thing, but catching them in the act - getting down and dirty in your bedroom with the woman from next door - will haunt you for the rest of your days.

Thankfully, however, there's one guy who believes he's sussed out a means of testing whether or not your partner is cheating - or even considering it - so that you don't have to go through the heartache of discovering the news yourself.

And that man is private investigator Ray Ranno, who has stated that during his stakeouts on suspected male cheaters, they carry out one very specific practice ahead of meeting up with their other woman that you should always be on the look out for.

Speaking on the Locked In with Ian Bick podcast back in April, he broke the news which left listeners absolutely baffled.

A private investigator has revealed the specific practice male cheaters typically do. (Getty Stock Images)

"If a guy's going to pick up his sweetie on the side, he wants a clean car," the American-born PI explained.

Adding that he'd constantly see cases whereby the unfaithful husband gets their ride well and truly pimped prior to seeking our their special someone on the side, he went on: "As soon as somebody goes to the car wash I think ‘Ha ha, what's next?’ It’s amazing how they do that.

"Women not so much. Women don't do it so much because they usually jump in the guy's car, men always want to drive.

"It's very rare that I see a guy jump into a female's car."

So, if your partner is suddenly bothered about the upkeep of their car, you might need to have some pretty serious conversations.

It seems that a clean car can ring warning bells. (LanaStock / Getty Images)

When it comes to other interesting aspects of Ray's job, he further explained that he's paid to gather as much dirt as he can on the cheating partner.

To do this, he uses his plethora of gadgets, including a long-lens camera for picture and video evidence AND a fake coffee cup with a HD camera inside - the latter being so he's able to tail and observe someone without rousing suspicion.

"If I go into a coffee place, or a supermarket wherever I need to be, I just take the lid off, turn it on, put the cap on and it looks like I'm walking around with a coffee." he said.

"Meantime, I'm videotaping everything."

What a job!