In Spelunky, you'll occasionally pick up a Hired Hand: some are locked in coffins, or hired hands can be purchased from shopkeepers. The hired hand will follow you around, occasionally getting distracted by something shiny and wandering off to break a pot or poke a monster. They're armed with a whip, but lack a good sense of aim or timing with it.
I've never found the hired hands to be useful; they like to break pots (occasionally releasing a monster) and wander around randomly, which attracts other monsters. They'll occasionally jump down pits that are watched over by arrow traps; while it's helpful that they'll take an arrow for the team, there are much safer ways of disarming arrow traps. They never really wander ahead of you, so the dangers they attract are the ones you decided to bypass rather than handle directly - and there's usually a good reason you bypassed them. The lives of Hired Hands are nasty, brutish, and above all short, and they've never seen a danger they didn't love. They're armed and can jump on monsters, but as far as I've seen, they're pretty bad at combat.
How are Hired Hands best used? Do they have any good points? Are there any reliable ways to make sure they're actually useful, or at least don't actively seek out monsters and poke them in the eye? Am I just missing something important about the care and feeding of henchmen?
(Bonus questions: Is the shopkeeper who sells you a hired hand for $8000 just trying to get rid of a useless layabout? Are the companions locked in coffins because they weren't good for anything else?)