Do you see increased sales for item specifics, does keyword stuffing work?

[futbolplayer]

I am an arbitrage seller and often leave the mpn and model number empty in my ebay listings. Reason being I am marking up the products and do not want buyers to be able to determine the source and find a better deal. My question is, is my thinking incorrect and will include the model number increase my sales?

The other thing I have been wondering is can you do some subtle keyword stuffing in item specifics to gain an SEO boost? Do buyer search queries match item specifics (without filtering)?

[james13v]

well, if people are searching using the MPN or model number, of course it would hurt your sales if buyers literally couldn't search your product using those things...

[james13v]

UGH!! They changed sizing from 16mm to 16 mm. With a space. At one point, they did the opposite. So I went in and had to change every single god damn measurement. Now they changed it back??? It's like they are ****ing with people on purpose.