People are going to complain if you give it away...not the right color, width, length. I think having a "quilters" sale helps as they are going to be glad to get 1/2 price fabric and know quality, so don't mix it with normal garage sale items, i.e., pots, pans, clothing, etc.
As for the shoplifters, shame on them. Dressed nice and nice car doesn't always mean they have money (maybe a lot of bills), but I would have called them out.