This past month was the first time I was every questioned about my luggage. I am Elite as I do fly a lot. This was the scam: I had exactly the same number of bags flying from the US to Europe as I did on the return, but my first flight was on Continental over and Lufthansa back. When I went to check in at Rome they said I had too many bags. I said I would take two bags as carry-on along with my briefcase. They said that was too many...but I knew better.
Then they decided to weigh my carry-ons and said they weighed too much. So I took stuff out of my carry-ons and put them in my checked luggage...which I am allowed extra weight.
Then they said that my carry-ons were too large (they are TravelPro, so that wasn't possible) and made me take them to a measuring rack. When they didn't fit, I told them to get out a tape measure because their rack was undersized.
Net result: I got all of my stuff on the same plane without having to pay probably $500 in excess luggage charges.
Still fuming, when I got to security, they had measuring templates on the x-ray machines and my bags fit through just nicely.
If I hadn't known my rights the Lufthansa would have ripped me off. Plain and simple.
Think about this: The professed reason for the regulations is because the extra weight costs more in fuel. In my case (no pun intended) the weight was perfectly fine; it was the distribution of weight that Lufthansa tried to exploit.
Knowledge is power.