I don't like them either because of the tangle problem and I've never felt their weight to justify pack room. However, we've got our long abandoned polycotton liners out of the store cupboard and put them in the van for hot nights in summer to keep off insects when we sleep naked. I'm toying with the idea of using one in the tent when backpacking in hot weather instaed of a sleeping bag. I wonder if a bag liner also has an application for use in hostels and hotels after hearing a friend's experiences of bed-bugs on the Camino last year.