Do I really need a dedicated travel laundry bag, or can I use a trash bag?

Across r/onebag and r/HerOneBag threads we read, a dedicated nylon or cotton laundry bag is consistently recommended over plastic for one main reason: breathability. Sealed plastic bags trap moisture and amplify odor over a multi-day trip. A washable fabric bag with a drawstring or zipper is the dominant recommendation, with compression bags treated as a niche use case rather than a default.