anyone know how to remove scratches from the shell of these?

Nobody gives a crap about the bottom - you cannot see it unless you’re servicing it, so it’s a moot point as long as the rest of the computer is in nice shape. As long as they aren’t destroyed beyond repair, don’t worry about it - realistic buyers who want a 2012 13” do understand it will have more wear and tear then a 2016-2020 machine. It’s the ones who expect a mint machine you’ll have issues with such wear, but they’re not buying older Macs like this.

In some cases, a buyer who doesn’t care as much about cosmetics may buy a blemished laptop to save a few bucks, especially if it is well equipped as-is. Unless the machine has severe damage like a dent on the edge of the Unibody (not cheap to fix, as you need to replace the LCD and chassis to properly repair it), a few additional scratches or a minor dent is not something I care about if the price and specs are right. Bigger discounts for anyone willing to take on a potentially expensive job like the LCD.

To give you an idea where this “blemish discount” comes into play, here is a realistic situation. Say I am looking at 2 machines - one machine has a Core i7, the Intel IGP and a hybrid GPU setup BUT is well loved and has more cosmetic issues (think more scratches, a small dent, etc. but no issues with the screen). The other is a nice Core i5 version of the same computer, but no IGP.

Discounted Core i7 W/ hybrid GPU setup:

• More wear and tear and often includes small dents.
• Better CPU at a low price due to the condition.
• Has a GPU with hybrid graphics.

Core i5 IGP:

• Specs are not as good, but is in better condition (easier to sell later on).
• Lesser CPU, so may handle some heavy tasks but you may know it more.
• No GPU - IGP only. This can be a setback in some applications.

If I had to pick between those two options and the price is similar, do you think I would care about the rougher cosmetics of the i7 laptop? NO. The CPU and graphics upgrade at a discount more then make up for any additional wear and tear! I would buy the i7 version, even if I get more looks for picking it due to the raw spec advantage.