Before you hire a CMMI consultant or SEPG Lead, at least check them out.

I have several clients who are in the process of selecting a CMMI Consultant or SEPG Lead. 

I offered to do a quick check just to get a feel for who was claiming to be a CMMI Expert.  I didn't do much:

I tried to add one of the candidates to an open appraisal, and I couldn't; it seems that they had some internal CMMI training but had never taken the formal class. 

I looked to see if another was an authorized/certified provider of anything and no luck there either.

Then I did the simplest thing of all, I googled them, and believe it or not, when I googled "firstname lastname CMMI", no results came up.  I thought you could google any three words and something would come up, or you win some type of prize.

There are a number of other simple credential checks that can also be done. Although no guarantee of finding a good consultant, at least you have a better chance.

Before you go through all the trouble of seeing if there is a fit for your business context, culture, project domain, etc. there are some very simple things you can do to thin the herd.  I highly recommend it.