That theory kind of breaks down when they get into specifics about military service, clothing, scars, etc. Things that a cold reader wouldn't have any access to.
However, a skilled cold reader will in fact get specifics (though they'll also have bad guesses), by making further general guesses based on the information you've already confirmed for them. For example, military service is very common for men in a certain age range, who were drafted to Vietnam. Clothing can be pretty uniform for people who you know to be/can guess to be in a certain demographic. Most people (beyond children) have scars.
If your comment was intended to suggest that some people actually can communicate with dead people: dude, no. It's not true. Your emotions are being preyed on for someone else's profit.
I'm not going to get into the over-arching point on a board inhabited by subscribers to scientism, but don't you think the jig is is kind of up if you're told someone has a scar through their right eye and they actually didn't, or that someone had a favorite shirt that has a tear in a certain place (that both of those things didn't exist, etc).
In other words, a level of specificity that is not so easily dismissed as a scammer interpreting the information they've been given.
Anyone with supernatural powers that takes that offer is a fool - their life would be effectively over. A person that could, say, see the future, is better off predicting the winning lottery numbers and sidestepping the almost certain involvement with government agents, or worse.
(Not that winning the lottery is statistically a good thing for one's quality of life either, which is a plausible reason that "psychic wins lottery" has never been a headline...)
This is about the future, but I think can be applied equally derisively to talking to the dead. Also My Dinner With Andre is a great movie so why not share it here:
"You had a family member who passed recently right? Or someone really close to you"
"Yes, yes! My aunt passed away earlier this year!"
"Ah, yes! And... and... she was sick right? Or in pain close to her death?"
"Wow, yes!!"
"You were close with her, or you were close with her family right?"
...etc