Neither have I. But if they did, you should show them something like this
Flannel is only best when it's recycled, so that means it needs to be purchased at a thrift store (or any sort of yard sale). Preferably, it has been worn by someone larger than you so as to get the full lived-in effect (don't steal from homeless people). This results in a poseur-free appearance since they are only being bought for comfort.
In conclusion, DON'T BUY FLANNEL IF YOUR MINDSET'S WRONG
Here are some guidelines to go by:
1. secondhand is key
2. material must follow
flan·nelNoun/ˈflanl/
A kind of soft-woven fabric, typically made of wool or cotton and slightly milled and raised.
3. matching should not be an issue, flannel should be carefree, there's no room for judgement