A 99 Cent Store just opened up a year ago a couple blocks from where I live and we've gone there quite a bit for last minute items or cheap products that are better off getting there than at say Target.
The store is kept fairly clean when I go there...no more of a mess than any other store I've gone to. And I like that you can get a lot of things on the cheap such as a small laundry basket, baby wipes or ice cube trays. Even most of the foods there are fine to get but beware of the quality of these products...many of them are in this store for a reason. Either they are very close to or way past the expiration date and they just simply are not the best quality product out there. We purchase some teriyaki sauce there once and within a couple months it had fermented into this awful alcoholic teriyaki sauce. LOL I've also seen candy there from Christmas during Easter time!
At the store I go to they simply don't care much about customer service, at least the managers don't. The last two times I've gone there I've found one poor cashier handling a line of 5 or more people. When the cashier calls for help the manager finally came to the register and said basically "sorry, we don't have anyone to help". Well, the manager himself should have done something. :P
Like many cheap products at the 99 Cent Store, you get what you pay for.