I can't get them clean. Despite many efforts with cotton buds, soap, boiling water...I throw them in sterilising solution, so I know they're not a health hazard, but... do you think I should replace them anyway?
Think I'm just looking for an excuse to be ecologicial and keep them, or be hygienic & toss them!
And is there a way to keep black gunge from appearing in there in the future?