The answer? Yes, indeed they do!
Mr Spraggons Den popped over yesterday afternoon (always a pleasure to meet the similarly afflicted...) with three of his LPs that were noisy & his current cleaning method couldn't cure. I can't remember the names of the artists; Mr Den will enlighten. Anyway, we stuck the first disc on my LP12 for an initial listen & it was a real rice crispies job, so we managed to fire up the venerable Moth (fortunately the battery wasn't flat) & gave the album a good old soaking and sucking. TBH I wasn't too optimistic, so it was a bit of a revelation to find the crackling had more or less completely disappeared. We ran it through the Moth a second time, which didn't affect things further, but nevertheless, the record sounded pretty good and perfectly listenable, just the very occasional pop.
We "Mothed" the other two LPs with similarly effective results in terms of crackle removal, but the third one had some very distinctive marks across the playing surfaces and the runout areas. My initial reaction was that this was some form of mould, having treated a shedload of LPs thus contaminated in the past. We only really noticed it when playing the LP after the initial Moth treatment, under the bright spotlight over the LP12, but regardless, the record played silently. We ran it through the Moth again, but this had no effect on these marks. I tried rubbing the marks where they appeared on the blank areas of the runout, but these marks were deeply embedded in the vinyl somehow, and IIRC certain moulds are capable of damaging vinyl. I guess luckily this doesn't seem to have adversely affected the sound. Here's a piccy of the marks under the bright light -