I was always taught handles down, because that keeps the eating surface cleaner (when they drip, which they will, and when the debris settles, which it does). People who do handles up seem to have less clean utensils sometimes…
We always put the handles up–even more so now that I’ve read the story in one of the cat magazines we get about a guy who found his poor little kitty cowering in the closet with his tummy cut open (I won’t describe the rest but I’m sure you can imagine) after jumping down and raking himself across an upward-pointing and very sharp knife (miraculously the kitty survived the experience–the guy got him to the vet right away for surgery).
We have three cats, so this hit close to home.
Handles down for me, although I only put eating irons in the cutlery basket, and crouch down next to the machine while loading (so as not to slip over and fall into it). For sharp kitchen knives, my dishwasher has a special rack insert which holds them lengthways in the upper basket, out of harm’s way.
Checking my owner’s manual, it explicitly states not to put sharp knives in the cutlery basket, and especially not with the blades pointing up.
Personally speaking, I always found the dishwasher didn’t get them clean if I put them upright, so I removed the cuttlery pot, and I now put my cuttlery down flat.
Handles down so it doesn’t dent up the blade when I drop them in from several feet up 