a scale used in a busy place can get off very easy. it depends on how often they have it proffesionally calibrated.

hubby and i own a gym and have ours done 2x a year, plus we check them by using plate weights all the time.

home scales, no matter the type, can get off if you keep them in the bathroom. the high moisture can cause rust inside.

the scale should always be placed on a hard flat level surface. never any type of carpet. best to always place in the same spot when weighing.

LOL..i sound just like i am at work.