Cleaning straw cups 😨

Question for anyone who uses straw sippy

cups for their kids, how do you fully clean the straws? We use hot soapy water to clean them and run water through, and let them air dry up right. For a while we thought that was fine but then my husband rolled up a thin paper towel and put it in one of the straws and a ton of tan, brown residue came out for each straw. I’m assuming no one actually hand dries their kids straws with paper towel after every single wash, how do you fully get the plastic straws clean?🥵