I am the happy owner of a couple fresh tubs of McC O&G and Mild Lemon, that I decided to decant in my two plastic smash boxes. The only problem is that one of them has been used for L260, which left some of its *other* scent (the horrible burnt tyre one), and I don’t know how to get rid of it. Any ideas? I tried leaving it open for a couple days and filling it with water and baking soda, but the plastic won’t let go of that smell…
Just press the Reset button, they all have one. Prob at the bottom. Little hole you have to put a paper clip or something in.
The most success I’ve had is to wash it with soap and water with a gentle cloth. Even then there is still a smell but not as strong. Maybe you should get some acrylic like the bullets as they don’t seem to hold smells the way plastic does.
Just wash it out and leave it open for a few days. Better still peg it out, outdoors on a line for a few days to let it air out.
@ Micheltn, I never found that reset button very successful, 
Smash boxes are cheap and you can never have too many. Buy a bunch more on your next order.
Believe me; one year ago I didn’t know what a ‘smash box’ was. I found out and find that I have three. I have difficulty opening them, and sometimes I don’t close then correctly and they open in my pocket! One day I’m thinking I’ll smash them…
Oooo yea…plastic smashboxes are hard to get the scent out. I personally don’t like to throw things out, even if it is just a 50 cent smashbox, although some of those larger ones are darn near $1!! ANYWAY, here’s what I do that seems to be fairly successful - Camel Back cleaning tabs. They aren’t cheap, but 1 tab will clean at least 10 smashboxes. I haven’t tried this method with a super menthol residue, but it works well with less ‘pungent’ scents. Good luck!
or you could buy some more from Tom @ $.50 each
I found the best way is to fill it with petrol and set it alight. No snuff smell left afterwards.
I must be the luckiest Guy alive. I don’t give a s–t what odor is left in any of my smash boxes!!! When one gets empty I just fill it with something else and keep on sniffing.
This next comment might open another can of worms but: Use the “plainest” like Rail Road Mills Scotch, give it a shake, let sit, wipe out next day. Plainest - any takers? 
Agree with Gimpy Ive got to say, filling it with another snuff should get rid of the smell anyway
In the world of pipes this would be called ‘ghosting’. Fill with salt and alcohol and let sit for a day is how it’s handled. Might be worth a try.
Have you tried vinegar? Some people use vinegar to remove “ghosts” from tobacco pipes. The vinegar odor disappears upon drying, supposedly taking other odors with it.
Put whiskey in it. Whiskey goes well with everything.