Dirty Chimney 

I think Dirty Chimney offers about the best 50 feet of readily accessible 5.0-5.1 climbing I've seen in the Northeast US. At most climbing areas, the easy routes are slabs. Leave it to the Gunks to offer one with interesting holds. It's fun to look for the "hidden" holds that make it only 5.0-5.1 (and avoid using actual chimney techniques).
Yes there is some dirt around (more if you go beyond the ledge on top of Laurel, all the way to the top of the gully, which I don't recommend) but most of the footholds and handholds are usually fairly clean (? except after a big rainstorm ?).

So if you just don't like climbing in enclosed spaces - or easy climbs - or short climbs - then of course don't do it (but then please don't whine about it).

If you are looking for interesting 5.0-5.1, perhaps intrigued by climbing in a 3-dimensional space, well here it is.