The OP said they were in NGS slabs.
TMI time. There were at least two companies that used that name for slabbing. One was awful, but sort of legit. The other was an anonymous basement slabber.
If they are in not so awful plastic holders with a label that has a bunch of numbers below the grade, they are the basement slabber. The basement slabber was one of the many do-it-yourself eBayers from the early days of
ebay. (Remember Centsles anyone?) This one sold coins that were described incorrectly, were wildly overgraded, were usually cleaned, sometimes plated, and sometimes counterfeit.
If the slabs are really cheap plastic and can be popped open with a fingernail, and have really amateurish labels from an old color printer, they are the kind of legit fourth-tier company. This one graded a whole bunch of cleaned coins and assigned straight grades to them. They used some buzzword for this, like "balanced grade" or "blended grade" or the like. At least they slabbed genuine coins.
Unfortunately, when my wife and I had our coin business, we saw
hundreds of these slabs in shows back east, like Missouri-Illinois-Ohio maybe 15-20 years ago. I'm guessing these slabbers were from somewhere around there.
I agree, if genuine, these are all AU-something and have been cleaned.