I only go to Joann's when I already know what I need and I take my coupons with me. If the item I need is not on sale, I use the coupon. If it is on sale, I might take the time to find something else to use a coupon to buy, but I've had the same experiences (applying discount to lowest priced item, etc.) so I don't use the coupon as my reason to go. Bonus if I can make use of it, but I'm not there because of it. In the past I've had a sort of 'wish list' of things I would use a coupon for if I'm in the store and one of those items is not on sale.
I also use the coupons for the pricey things like Ott Lites. But when they 'reduce prices' so frequently on things, I'm with those who just wish they'd lower the prices and forget the coupon foolishness...
Having said all that, I just got the flyer with some good savings on fabric July 11 to 17 (some 50% off) so I'm making my list since I'm gearing up for some Christmas stitchin' and I'll take the time to browse to see if they have interesting fabric.