I don't think it is bad in itself. However, if you go to firms you may have an issue explaining why you did it versus working for a firm. (ie, do you really want to work for a firm, why didn't you get a firm last summer, etc.)
Another point: I HIGHLY recommend working during your 2L summer at a place where you would like to begin your career, and try to get an offer this summer. I cannot stress this enough.