Sticky refers to conventional "Stick Built" trailers, the kind with flat surfaces and lots of edges and seams that can leak.
Apparently NADA goes by declared prices paid as reported to the DMV or state government. Most FGRV's are
sold private party to private party and actual selling prices are reduced when reported to reduce sale tax consequences. With sales tax at almost 10% in CA, every $100 you knock off of the claimed sales price is $10 that stays in your pocket. As a result, NADA prices for RV's over 5 years old are often 1/4th to 1/3rd typical selling prices.
I am only reporting this phenomena, I am not suggesting it or recommending it.....