I think that if you ever accelerate hard enough out of bends to get the front go a bit light and floaty then consider a damper. That is the situation which seems to cause the most wiggles: leant over, but pulling on the inner bar to come upright (you do it even if you don't think about it...), hard on the gas, ripples or other bumps in the road.... its happened enough times for me to know not to push it so hard in those situations.
I had a fairly serious one in front of quite a big crowd at the Isle of Man (2007 TT) coming south out of Kirk Michael just after roads re-opened (so pretty much first on the road in that direction). First right hander goes through a little dip and up the a hill and the crest of the dip caused a big slap as I came onto the rise. I actually heard the cheers from the people on the bank through my earplugs! If the crowd hadn't been there I'd probably have shut it off a bit more than I did. SERIOUSLY considered a damper after that....
I tend to ride around it now, but I do think about it, and it would be nice not to.