Replace inner sleeves on used records?

I use Vinyl Storage Solution products - who are running a sale on their products.  I find them top quality, excellent pricing, and great service.

I do. after they are cleaned ultrasonically, vacuumed and they are then placed in a MoFi anti static sleeve.

Non ordinary original sleeves are totally good for keeping, specially if containing some art or printed info. Usually I keep them inside of the hard sleeves next to the records stored in new inner sleeve. 
I do dispose basic regular paper sleeves due to dirt and dust contamination. After the washing of newly purchased old record I put new plastic anti static sleeve on and old one goes to the trash. 

I usually do keep them for future value purposes if they have something on them that applies to the recording. If they are just plain, I pitch them. 

Yes you should and along with double albums make sure you check for marijuana remnants.  Can usually find enough for one hit!