What happened to the good ‘ol days when husbands or wives going through messy divorces would hire some doughnut-eating, bad-suit-wearing private detective to track their spouses – but who’d fall asleep in his beat-up ’88 Oldsmobile and miss all the good stuff?

That’s how it went in the movies anyway.

Nowadays, in real life, custom-made trojans have replaced binoculars. At least they have in one high-profile divorce.

It seems the American banking heir husband of British Jimmy Choo shoe boss, gorgeous Tamara Mellon, hired a UK-based private eye company called Active Investigation Services, who in turned hired a hacker, to email Tamara a keylogger. The payload arrived in Mellon’s inbox as an email claiming to show what her husband was up to.

Like any gossip-hungry spouse going through an acrimonious divorce, she clicked. Unfortunately, she was socially engineered and got a silent trojan installed on her PC, which tracks every keystroke.

Well it appears the days of tailing cars, tapping phones and guessing passwords are behind us. At the same time, this spying technique exemplifies a new trend in malware.

“This is going to be far more regular,” Dennis Szerszen, a senior vice president at SecureWave told me Thursday evening. “The most effective crimeware is going to be focused on targeting specific individuals. Gone are the days of broad mass popular malware.”

If husbands such as Matthew Mellon can have this much success, think of what a foreign government or a major crime organization can do with many more resources, Szerszen wondered.

“It really does put the onus on us to be diligent and a little more knowledgeable about security than we probably want to be,” he said.

I see it as less challenging.

The same rules apply to phishing emails as have applied to hundreds of years of scams: If it’s too good to be true, it probably is.

Like the other night when a $300 debit card showed up in my snail mailbox. The catch? I had to provide some testimonial for a federal student loan company or something like that.

I’m sure I was going to be asked to do much more, but I told the guy on the phone: I’d rather burn $300 than stay on this call with you.

I hung up, like Tamara Mellon should’ve hit delete.