Yes, for the most part they are quite based in reality as much as I don't want to believe it either.
What they fail to take into acount is muscle mass and bone density. (example, Arnold was about 220 in his prime)
A better measurment is definatly body fat %. A bathroom scale with body fat analysis is relativly inexpensive (about $50), and easy way to track your fitness progression. I'm sure it's not the most accurate tool by any means but should be good enough for rough ideas. This morning I weighed in at 208 with 20% body fat meaning that I have roughly 40lbs of goo left on my frame. If I weigh myself next month and find that I weigh 210 and have 18% body fat then I know that even though I gained weight my fitness and muscle mass increased so I won't sweat the extra pound or two.