Every procedure of testing bodyfat has a small margin of error (even bod pod and hyfrostatic weighing). Simply put, there is no 100% full proof method to find out a persons bf%. Some people claim to have 1-2% because calipers couldnt pinch their skin (if your lean and thin skin) while most contest bodybuilders have been measured now at 4-5%. Also, some people state that no one truly gets under 7% because thats whats needed to maintain organ function. I could personally careless what a formula or read out sheet say my bodyfat is. I go by the mirror and spots where i tend to hold my fat. Clothes are also a good measure, but can also be decieving if your carbs are low and muscles are slightly dehydrated.
Pictures also serve as a great tool and dont lie. I have had my bf% taken w/ numerous methods and my suggestion is this. When you start a diet, have someone run a bf test using one of the methods. And every 3-4 weeks go back for a re-measurement not to find out exact bf, but to see if your making progress. Jut stay away from those damn tanita scales, they are a joke. Did anyone see Dennis James' video? He jumped on one and had it measure his so called bf% and it had him at 14% and he start at 12% 8 weeks prior. Mind you he was ripped to hell and 4 weeks out from the O', so that shows you how accurate that method is.