There is some merit to your freind's "secret". Meat eater's definitley exude predatory scent, its been very well documented. However, I've yet to see a deer run from a fox, mink, raccoon, or other small predatory mammal. I'd suspect that while "meat eating" some scents are important, its not the limiting factor in hunting situations. A deer may spook just as quickly if you place gasoline in a food plot. There are other scents that we produce that are decidingly HUMAN, and deer cannot differentiate "good" (read: vegetarian) human scent from bad (read: meat eating) human scent. In other words, scent control is still paramount, as is hunting the wind. Some foods, "enhance" our scent like garlic, or meat. If you play the wind correctly, you could probably harvest a deer, while barbecuing a side of deer.

My point is, there are very few cure-alls in scent elimination - its still important to hunt the wind correctly. I for one wouldn't give up my backstraps fried in butter for any deer!