Buying an RV... How long has it been on the lot?

When we were browsing used units at the local Camping World, the sales guy (new to the business) showed us the arrival inspection report for the 2004 unit we were interested in. The report showed what they found upon inspection and what they did (or didn't) replace - but what was most interesting to us was how long the unit had been sitting on their lot - over a year! (I found out later they have some used units they've had for 2+ years!!)

We managed to score a pretty good deal (at least, a price we were VERY happy with) on that unit. Hard to know if age-on-lot was a factor in their decision to accept, but it certainly influenced our negotiation process.