I've seen more than a few sets come loose and figured out what happened to all but one set. 

 One set was a Ford 1ton and some genius didn't mate the mound and dimple holes correctly (the original alignment stud had broken off).  Driver didn't hear or ignored the funny sounds from behind him when they started to loosen, holes in rim got ovalled terribly, and the studs either broke from the chewing or the nuts pulled through the enlargened holes.  Wrecked the drum holes as well.

 Same Ford 1ton, drum and rims replaced, new studs etc, idjit didn't tighten the nuts to finish the job, someone else jumped in a few days later and the truck didn't make it 20 miles before the setup was wrecked AGAIN!  Same scenario as above but the driver was quite a bit brighter and pulled over before the wheels fell off.

 One set was a Chev 1ton that someone threw a Ford rim on the inside of the rear duals so that anybody looking couldn't tell that a dimpled rim was being used with a flat center rim.  Dense driver, wheels fell off at highway speed on a divided highway at night and almost took out two startled deer on the right side of the road (wheels were from the left).  Found the Ford rim, don't think we ever found the Chev one.

 Ford 1ton I was driving, water tank on the back, left handed offramp corner and the right-hand studs spontaneously shattered and both rims followed AND PASSED me down the offramp, crossed the road through a stopsign, crossed two vacant lanes of traffic, and bounced off the opposing curb, crossed a vacant crosswalk, and rebounded off a hill to wobble downhill and stop on the road.  Rim holes had no ovalling, so they didn't come loose and I didn't hear it.  My guess?  Overtorquing or long life caused metal fatigue and hitting the sharp bumps while loaded on a corner caused them to let go more or less all at once.

 If they slowly came loose, the rims and surviving studs will show lots of wear and chewing.  Driver should be able to hear/feel the slowly destructing rims (IMHO) even if he doesn't know what exactly is happening.  If they spontaneously shatter, the rims look good and are reusable and there's nothing the driver could do to prevent the accident.