[Jetliner]

It does happen at times, but from what I've seen and what I'm told still happens it's only when it's obvious. If there is a soft sided golf case and it's quite spongy when you pick it up, it's obvious it is full of clothes. So the passenger may be asked to open the bag.

What everyone needs to keep in mind is this - the normal weight limit is 50 pounds. Sporting equipment can be heavier, so the airlines take that into account. You also have to think about size. A golf club bag is larger overall than a regular suitcase. So, by doing what Jim is saying, someone with sporting equipment could royally get screwed on size/weight fees. The whole idea is to keep bags under a certain weight for free, while giving some leeway for sports items. So also by Jim's rational a suitcase could be over the 50 pound limit, but that defeats the purpose.