With The Real World: Las Vegas, the reality series, in its 12th season, has taken on an air of grimness. Remember when the lucky little MTV-selected pups used to gambol into their plush new house and squeal delightedly at all the bright colors and decorations (oooh — a fish tank!) before gradually, week by week, discovering that there were snarling junkyard dogs among their number? The latest ”seven strangers” arrived with teeth bared and belt buckles loosened — they couldn’t wait to snipe and (if I hear this phrase again, I’ll, I’ll…throw a fork at someone!) ”hook up.” In fact, crazed horniness seems to be the staple, like when Steven says of housemate Trishelle, ”Her breasts are always on my mind.” It would require the Vegas forensics team of ”CSI” to locate a fiber of shame among these seven hollow souls.