If your baggage weighs more on your return leg of your trip but not on the first, (with no added items, of course) insist it be weighed on a different scale at time of check in! Nothing can be done at customer service except insult your intelligence. This situation came up, and at check-in I told the attendant that it should not be heavier than when I first checked the bag. She looked at be with a blank stare. Customer service said I should have had it weighed on a different scale. That's admitting their scales are not accurate.
Their scales are off! And NOT to YOUR benefit. I was told "the items may have shifted in the luggage causing it to weigh more." Hmmm. Really? Blame it on American greed, employees who could care less about paying customers that provide them jobs or poor customer service, but i will be selling my stock, I need my $25 back and I'm embarrassed to have ownership this company.