It also helps me sort of budget what I buy, because I just fill those two bags for a trip, and thats my groceries for a week. sometimes 2.
Yesterday, I got my stuff picked out, then went through the line(had a few too many items for self-check). Hand my canvas bags to the bagger, who starts bagging in one of them. The cashier picks up my other bag between pinched fingers, making an "ewww" face, and says "i dont know whose or what THIS is" and starts bagging into plastic. The bagger and I both at the same time explain that I brought my own bags. The cashier then begins to ARGUE with me that there is no way everything I got will fit in just two bags(which it does. i do this every week). She just gives up, hands me part of my stuff in a plastic bag, and lets the bagger finish, then turns to the next customer to bitch about how stupid it is to bring your own bags into the store when you can get plastic ones for free. Wasn't worth getting a manger over, just really kind of rude to start talking about it while I was still standing there.
Though I can say its the first time it's happened, and the bagger is one I've had before(and always compliments my bags, because they're pretty fun looking, and she's amazed by just how much they hold)