Not Sure I Agree
I think I would rather buy a boat that had not been covered then a boat that had been covered incorrectly.
I have seen a number of boat that have tarps that are placed over the hatch and cockpit that actually could do more damage then the snow.
I looked at my old boat this weekend (sold in October). The new owner placed a tarp over it to "protect" it from the snow. But the way he put it on the boat, the scuppers for the cockpit are covered and when the snow melts or it rains, it will just fill the cockpit.
Another boat (a friend of mine owns this one and I have suggested he change the system) has a wooden stand in the cockpit and then a tarp that goes over the live lines and is tied together under the boat. The snow load is pulling the stanchions in towards the cockpit.
Then when it comes to shrink wrapping, many of the boats I have seen "professionally" done, have the shrink wrap extending down the hull to the water line. If you go up to one of the boats shrink wrapped this way and pull the shrink wrap away from the boat, gallons of water will spill out. That water is trapped between the shrink wrap and the hull and will promote blistering. Then there is the fact that most shrink wrap jobs are completely sealed and that will promote condensation inside leading to mold and mildew.
My new boat came with a canvas cover (and I would have bought one if it didn't) that goes over the boom, around the mast and stays and down to the toe rails without going over the stanchions. (you can see it in the attached photos)
Unless the cover is constructed like this one or with a good frame, it could do more damage then it prevents, IMHO. After all, if you are up-to-date on your other maintenance (i.e. bedding hardware, windows, etc.) what damage will the snow do?
“Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover.” -Mark Twain