While most of the pro's do catch some fish, many are just trying to find bites. In many cases, they bend or remove the 'hook', so that they can just feel the strike.
A common problem in local tourneys, is the guy's who go out on Friday (for a Tourney on Sat), and find the mother load. Caught 12 yesterday, from this spot. Then on Sat., caught 1. In some cases, the fish get what many anglers call 'sore mouth'.
Tox is correct in that some fish on a bed will strike at a bait, regardless. Some won't. Last year on Santee, it was generally reported that many pro's had to work for 60-90 minutes to get one good strike off a bed.
One of the 'unwritten' rules of tourney fishing (especially by the pro's), is not to hook bedding fish that you can obviously see. What many will do when they can see (or sight fish), is simply use a bait to see what they will strike at, but without a hook.
Tex