Yep, they're nasty, not only the liquid spills, but also sort of evil gas that ruins everything metals.
Examples :
Watch how the shiny battery contacts from my Fluke 287 turned into ...


The culprits, and this photo was shot at Oct 2013 and watch closely the battery's expiration date, no, they're not drained at all.


At April 2017 .. brand new never used alkaline cells, fyi, they're genuine product.
