Okay they arent bad, ie they are a pretty big lot with a wide selection of cars. They do have a lot of older MB's. Most if not all are auction cars, having come from manheim, adessa, or rarely NADE. This is the case for i'd say 80% of the used cars out there on independent dealer lots. Dont let it scare you on it's own, but just know to keep your eyes open. When a dealer buys a car at an auction, it's a 30 second decsion. I've been there many times. And sometimes all that glimmers isnt gold. Granted they are buying wholesale, but chances are their cars arent from the MBCC lane, but rather from some other independent. MBCC often times practices the MB dealers only policy when it comes to the newer stuff, especially anything that can be starmarked, even though you'll never find an MB dealer that admits going to the auction, they're there.
They probably wont know the true history on anything they have. Dont believe any one owner trade stories. Get everything in writing, service history etc. Also take the car to a good independent, I Recommend the German Car Shop in Edison, NJ, just for proximity reasons, but be forewarned that they are often very busy.
They cater to a more "urban" if you will clientelle, hence the plethora of older luxury cars. They are one of these no credit no problem dealers, and henceforth most of their clientelle is ignant to anything but the 3 pointed star on the hood, and getting approved, so dont be surprised if their knowledge of MB's is average.
Im not saying that there is anything wrong per se, i.e. no "rumors" if you will about their practices are circulating in the industry. Things often dont get fixed right the first time though, and they will use the cheapest parts they can get their hands on. 99% of the time non OEM. They are big time negotiators, although whatever you intend to do, tell them you are paying cash, and want an out the door price, once you settle on the price, then arrange financing if needed.
Since they are heavily involved in sub-prime financing, they will often make the numbers seem attractive, only to make a few points on the back end, off the loan.

I hope this helps. Again, I havent personally bought from them, but just to give you a little bit of an insider's perspective into the industry, and to the type of operation that they run.

Personally stay away from the Newark / North Arlington area dealers - Regardless of price. There are a few exceptions, but if you've heard about it, for the most part, it happens in Newark.

Let me know if I can be of any further assitance
Best wishes and take care,
George Androulakis