Yep watering the track once rubber is laid down doesn't help a lot. What helps a dirt track is all the prep during the week. By the time race night comes the track should have enuff moisture to hopefully come up once the sun sets on race night. Most dusty crappy tracks are the result of not taking proper care during the week. The raciest track I ever saw was in the process of being ripped up deep for the next race night while the pits were still full from the current nights racing.
Never been to Eldora but from what I've read, seen and been told it can be way better with a little effort from the owner and crew.