WARNING! Having worked at Tower Records when they were still selling LP's (late 80's), I can tell you authoritatively that an LP in "still"-sealed shrink-wrap is NOT necessarily new. Huh? Tower (and I'm assuming other retailers) stores had a shrink-wrap machine in their back room; when an LP was returned to the store by a customer (for various reasons, sometimes only because the customer didn't like the music) it was put on a backroom shelf awaiting the store's monthly return. Record retailers have to pay a penalty to send product back to the distributors for credit (a little more than a buck a disc back then, which they would obviously prefer not pay), so one of the shipping/receiving clerk's responsibilities was to inspect each customer-returned LP and determine if it could be sold again. The attitude was, some consumers were more picky about surface noise, warps, etc., than others, and that a returned LP might be perfectly acceptable to another customer. Plus, as I said, some were returned for a reason other than a defect.
So, if the clerk found the LP to look fine (and believe me, they didn't have audiophile standards or sensibilities, being normal "civilians"!), he would put the LP (in it's jacket of course) into a length of the plastic film that was on a roll at one end of the shrink-wrap machine, seal the open end (the film was a "tube", open only at the two ends, so one side would need sealing---the other open end of the tube being already sealed from the last LP that had been done, if you can envision that) with a heated electric "press" (which created a rough edge in the seal, with tiny "beads" of melted plastic), the LP/jacket then run through the small heating oven (warps anyone?!) at the far end of the machine until the wrap had shrunk tightly on the jacket. Overly tight, if left in the oven too long. The way to identify such a resealed LP it to look for the two "rough" seams running along two of the four edges of the jacket. Unfortunately, some seals didn't produce the rough edge, looking just like some factory seals. Great, SOMETHING else to worry about!