They really are. I've owned a Chinese one and a Yugoslavian one. No cleaning needed. I've seen them in mud or sand, shaken out and had 90 rounds run through with no jamming. The only time I ever jammed any of mine was when I used some East German plastic tipped training rounds. I assume they had low powder in them.

The professional problem with them is they're noisy. The loose tolerances, which make them jam proof, are just too clunky if surprise is important. They're great in a battlefield situation, but we're not really fighting battlefield style right now.