We use metal cookie tins which we line with waxed paper. I've also successfully frozen them.

I use plastic tupperware but I have four kids so cookies never last long here! ;)

I always put a slice of bread in the cookie jar. I don't like hard cookies and the bread keeps them soft. ;)

What kind of plastic containers? Perhaps the containers already had an odor from the previous contents. Even with good cleaning sometimes plastic containers retain a smell.

THat's what I was going to say also - plastic containers retain and then pass on odors/tastes from prior contents. I recently stopped using plastic for that reason.

On a similar note, have you ever purchased something like baked goods that are kept in the same case with other items, like salads or meats and noticed how off the baked goods taste? Baked goods absorb orders easily.

I like to keep cookies in a tin rather than plastic container. I think the plastic does change something in cookies even if it is a brand new washed container. I do use plastic for everything else and I don't notice a difference. so I guess that makes me a cookie connoisseur or cookie monster! LOL

I dont have kids and still cookies don't last here! I don't like that cookies get soft in plastic-- I assumed it was a moisture/off gassing thing. I freeze.. it helps with portion control and cookie quality. I freeze baked cookies.. and also cookie dough.