They even once saved a plane from the pudding cup my daughter left in her backpack (which naturally earned her a pat-down).
My wife, then-infant daughter, and I had an interesting experience flying in the US: we often traveled with pre-packaged, ready-to-use UHT-sterilized bottles of formula just in case (a) my wife's milk production was insufficient at that moment and (b) we didn't have sufficient time or access to things like boiling water needed to make powdered formula. Since opening the sealed bottles defeats the point of UHT sterilization and starts the ~2 hour countdown after which the formula must be discarded, we asked them not to open the bottles.
Typically this was no problem: they did some swab tests, x-rayed the bottles, and concluded that they were (correctly) harmless. Additionally, they said that not opening the bottles meant that either my wife or I needed to get a pat-down but they let us choose who got the touchy-feely treatment. Obviously, any bad guys would have the one without concealed contraband get the search, thus defeating the purpose of the search.
At least that was better than Newark: the security screeners said they needed to do the swabbing and other tests before letting us proceed. However, the checkpoint was quite busy at the moment so they just had us stand around next to a table holding the bottles, my laptop, etc. for 10 minutes or so, then let us collect all the stuff and go. At no time were any of the tests they mentioned actually done.