If it isn't going to affect my fishing I see no harm in helping others out. You've got to be a bit careful if you get onto a "secret", ie the existence of a big carp, barbel or pike, because there are glory hunters amongst the specimen fishing fraternity who will jump on the back of your hard work. But if someone wants pointers on a stretch I know I'll always give them.
All rivers are better for barbel with extra water on them, however after a dry spell there can be so much weed and shite drifting downstream, that it's extremely hard work, recasting every few minutes. Plenty of Ribble barbel are caught in the night in low water conditions and I intend to try to prove that this evening.