DO NOT BADMOUTH Sears at an interview. As tempting as it is to talk shop and 'get friendly' with an interviewer, don't do it.
My trick when asked these kinds of things was 'yeah, Sears has its issues, but I accomplished blah blah blah during my time'. Turn it around to show you can work in tough situations, and get the job done even with roadblocks and stuff.
Good luck interviewing.
Really good advice, OtFRMjC-1hwn. This is very important to take a note of. My wife is a GM at a restaurant, and she says that one of the first red flags for her when a potential employee comes in for an interview is when they start harping on their previous place of employment. It is not professional, as true as it might be, and not relevant for the new position. The above advice is excellent.