If there is anything that needs to be correct, it is a scales for weighing people. Women often do not want the scales to be wrong when it shows that they are weighing more than they actually are. Often times, people think their scales are wrong because they think they should be a smaller size and they want to be of less weight.
However, if a scales is actually wrong in the amount of pounds, then the scales are not totally bad. They may still be reliable and not a piece of junk, but their results are not valid. Reliability of an object means that the items is performing consistently the same as these scales were. Validity refers to the outcome being wrong.