Is it any coincidence that my Howard low with plastic mouthpiece D and my plastic Dixon high D, which both live in those natty two-part plastic cases both smell a bit funny sometimes?
I thought I might melt some holes into the cases at the mouthpiece end to encourage airflow, as it must be the whistles are damp although I do mop them and leave them out to dry after use - obviously not long enough.
Anyone else experienced this?
That old whistle that turned up on Norfolk Island also smelled funny…but maybe for a different reason.
I’ve not really had trouble with stinky whistles, but I see nothing wrong with running some warm soapy water through them and then rinsing them well.
I wouldn’t want to put a bad-smelling instrument anywhere close to my mouth.
–James
I’d like to think of it the other way: I wouldn’t want to put a whistle in a bad-smelling mouth. 
I always like to have a “clean” mouth when playing. I never play right after eating etc.
I think this is because these nifty two-part plastic boxes are airtight, and gives bacteria and so on a nice chance to grow. In other words: Don’t store them in there, just use them for transport! I’ve had the exact same issues. Just take them out of the plastic boxes as soon as possible, and dry them off before and after putting them in there. Also, wash your whistles 
I agree with Theo. I once bought a Chieftain Low D in Amsterdam. A plastic box came with it and in the shop they told me to never store the whistles in it. They are only to be used for transport.
I agree with everyone else here. If by “funny” you mean a stinky smell, rather than just a plasticky or metallic sort of smell, then wash those whistles and let them air dry completely. I drip a little soapy water through mine and wipe off the outside each time after I play it and let it air dry. I made a sad-looking case out of a cardboard tube so that I can put it in the case and the water can still evaporate. I, like Ostekjeks, brush my teeth or swish my mouth out with water if I need to practice after I’ve eaten or been drinking coffee or juice. I didn’t do any of these things on my first whistle and it got crudded up to the point that it was affecting the sound before I realized what was going on 
. Now I never have to have a long session of cleaning my whistles.
While I wouldn’t go as far as Cynth, I can recommend people to never, never EVER play a whistle just after eating toast. This was a public service announcement.
I used to drink coffee with quite a bit of milk in it while I was practicing, just a sip now and then to “wet my whistle” so to speak. I won’t go into details, but it isn’t just vapor from your breath that ends up in your whistle! TOAST! 
Oh icky!!!
I am usually playing between sips of guiness or jamesons. 
i clean it irregularly. All is well, no stinkyness.
Alcohol kills bugs. There really is a potential for
little critters to colonize whistle heads, and plastic
is certainly prime residential property.
Midleton Very Rare Irish Whiskey is the only thing that really works. You could even put some on the whistle.
Philo
Ooh! Can you export some of that to the Netherlands? I really need to… ahem… clean my whistleheads. Yeah. That’s it.
MMmmm middleton. Now you got me thinking… im at work now, but it is friday afternoon. 
I’ll be washing my whistle every now and then in the future, and avoiding peanuts and porky scratchings from now on at sessions (unless all the tunes I know have been played then - pow!)
spot on sugarfoot - there is nothing worse than a dirty whistle.
Does anyone recommend steeping it or can this effect the mouthpiece?