Many people in the numismatic community affectionately refer to B-rate grading companies as "third world" companies. I am referring to companies such as NNC, SEGS, NTC, SGS, WCG, and others. They frequently encapsulate cleaned coins, damaged coins, and even counterfeit coins! All coins in these companies' slabs should be treated as if they were in a plastic flip. The grade is only a guess at best, and completely erroneous at worst.

Third Party Grading Services such as NGC, PCGS, ANACS, and ICG are trustworthy. They know what they are doing. Sure, they all have their flaws, but they are all much better than the aforementioned "third world" grading companies. These "top tier" grading services know how to spot problem/counterfeit coins and will return any coin they deem unworthy to be encapsulated and graded by them.

Also be aware of so-called "self-slabbers" on eBay. Some people will buy a holder for a coin, put a coin in it, and stick a label on the plastic. The grade may be as much as thirty or forty points off of the actual grade of the coin. Do not be fooled by these. If it looks too good to be true, it usually is.

To recap,

Acceptable TPG's:

NGC, PCGS, ANACS, ICG

Sub-par TPG's:

SGS, NNC, NTC, SEGS, WCG, and others

I hope this guide has helped to inform you somewhat about what to look out for when purchasing slabbed coins off of eBay. Thanks!