Hey Lizzie, I do the same thing...although I make sure I've peed a couple of times first
(I have a great nurse at my doc's office that says I can even take off mascara before getting on the scale there if I think it will help...every little bit does, ha ha.)
Anyway, I have a Tanita body fat scale. I can't vouch for the accuracy but it is helpful in terms of comparing me to myself in previous weeks / days. For example, if it says my body fat is 27%, it may or may not be 27%, but it's probably safe to say that it's less than it was the previous week when it said 29%. I would assume "reasonable" accuracy or there would be violations of truth in advertising and all that, but who knows?