Several posts on this thread have explained why it may be beneficial to clean a new LP, but the proof is in the doing. I've tried it both ways. In virtually every case a *proper* cleaning improves information retrieval.
I agree that improper cleaning would make a new LP worse, but neither I nor anyone else would recommend that.
I'm not taking my brand new car right from the dealer to the car wash.
Me neither, but I would never take any car to a car wash. That would constitute improper cleaning... car washes are death on high quality auto finishes.
OTOH, any serious collector will properly (i.e., hand) wash a new car immediately after delivery. Impurities are invariably imbedded in the factory finish. Leaving them there invites further detioration.
Don't believe me? Try brushing a silk handkerchief or a piece of Saran Wrap lightly across the surface of any new (supposedly) clean car with the back of your hand. It will catch and snag on impurities you can't even see.
These impurities can and should be removed by proper cleaning (e.g., by claybaring). Once the surface is truly clean, that silk handkerchief will glide so smoothly it's like the car isn't even there.
Follow with a high quality sealant or protectant and the surface will be so slick you can't even stand a water bottle on the hood of the car... it'll slide right off under its own weight.
Visually, the result is a show car finish that puts any dealer car finish to shame. Use the right products and it will last for years too. My 4yo Land Rover routinely slogs through snow, salt, muck and mud in ski country. Yet it looks better than the day I picked it up from the dealer. I'm regularly asked why. It's because it was properly cleaned before it was a week old.