L.H.
I haven't tried this myself yet, but pipe cleaners might do it. They're skinny & fuzzy so you can slip them through the nooks & crannies & work them around until they're clean. Just a random thought that crossed my mind when I saw you mentioned the straw kind. But honestly My best friend has three little ones & she just tosses everything in the dishwasher & she's had no problems as of yet.