Boxes of books weighed on a postal scale should let you calibrate your analog bathroom scale. You can graph how your indicated weights differ from the postal scale weights.
For smaller weights I trust supermarket scales more than postal scales.
My digital scale shows to within 0.2 lbs but the maker is silent on the issue of accuracy except to say it's not for commercial use. It was right on for 44.00 lbs.
Asking about accuracy and alleging cheating is bad for business!