It's really bad. The mere mention of the words "seagull/fumar vomit" by you brought back the memory of that smell, and now I feel sick. You've spoilt my day.
In reply to Gandalf:
There is a solution to burning. Soak your clothes in 50/50 hot water/vinegar. It does actually work, despite sounding like a bad recipe for fish and chips.
willelliott21 Aug 2010
In reply to yogoaqpw: Heard they used to collect it and use it as fuel on some scottish islands
In this programme they mentioned that should you get the stuff on your clothing, throw it away. It is the oil that stops it washing out, luckily I just got my hair cut off when I got it on my head.
According to Wikipedia fulmar vomit is an "energy rich food", so you could just lick the stuff off and use the energy boost to get you to the top of the route.
Eat nothing but pickled herring and anchovies for two days, the stick your fingers down your throat. Catch what comes up in a bowl and leave it in the sun for a few days until it ferments and thickens. Sniff.