@Hal & mole - Exactly the answers I wanted to read, good stuff
Just playing devil's advocate and generating discussion so people get both sides and don't take one or two posts as gospel
Stands to reason that you should protect any lens from risk of flying debris and not with cheap nasty filters either. That's a given. My UV was a Hoya even though it was only attached to a budget zoom. However, I'd say that in more 'general' use a lens hood does as much for avoiding scratches as a UV but without the associated drawbacks.
Dust is a different matter, a few specks on the lens have little or no effect and optical grade glass is pretty damned tough so can withstand a lot of cleaning - whether the coatings can or not though is a different story...
And of course, not much will save a lens if you drop it
I agree that
sensible use of a quality UV filter is a very good idea but it's not a 'fit and forget' item - I'll be using one for racing pics and dusty conditions, but also leaving it off a good deal of the time.
@Cooper - sorry if I've dragged this too far off-topic!