That probably won't do you any good if the pre-baiting is done properly John, you will still catch fish if you fish well, just as you would in any other fish holding swim...but the bait put in by the other angler is unlikely to help you to catch more than you otherwise would. I have only done it once, in a similar manner as that described by authors such as Miles and West, using very high quality boilies over a prolonged period during the closed season, and did very well indeed. I should add that I baited up several swims, so the fish were not concentrated in one swim...they were just used to a particular bait and trusted it because they had safely eaten it for several weeks.
That way this method of pre-baiting does not mean that another person fishing such a swim, using a different bait, will not catch (that idea is a red herring, an unfair criticism used by those who dislike pre-baiting) All it means is, if that angler gets into the swim he has baited and uses that specific bait....he is likely to have a field day....because the fish are less suspicious of that bait and have grown to trust and enjoy it. Fishing that swim with another bait means the fish will regard your bait in the same way as in any other swim...they will take it if fished well...but not with the gay abandon they would if it were the bait used in the pre-baiting campaign. In other words, that angler is likely to benefit from his efforts if he gets into that swim...but to you, using another bait...it is just another swim.
Cheers, Dave.