The most serious problem with this is that the food chunks may dry out, but that won’t kill bacteria, just put them to sleep. So the chunks themselves are a potential source of food poisoning.
You’ve prepared a meat dish by cooking it and effectively sterilising it, and then you’ve let it cool for 15 minutes while eating it, and probably another hour before washing it. In all that time the meat residue has had time to grow bugs. Then you wash it badly and let it dry. But the bacterial count is still just as high as ever.
Then you get that same piece of cutlery/crockery and use it to inoculate a nice piece fresh of chicken during preparation. It’s about as sensible as taking the fresh meat and rubbing it in the dirt.
And just like rubbing uncooked meat in the dirt it’s not really a problem provided that you don’t give the stuff time to grow. Take the meat, inoculate it and cook it within 20 minutes and there is no problem. The problem comes if you are using the dirty implements to prepare food for storage. Then you’ve got problem’s. You’ve introduced a nice load of potentially pathogenic bacteria into some fresh potato salad that’s then stored rather than being cooked. They bugs immediately start to grow rapidly and a few hours later the food is guaranteed to have you living in the bathroom for days.
Like most unhygienic practises this one isn’t guaranteed or even likely to cause illness on any given day or even any given month. Of course the same is true of not washing your hands or having a rotten sheep carcass in your lounge room. Realistically none of them will give you any illness most of the time. But none of them are good practices because they represent cumulative small chances of very serious illness. Every day you spend not washing up properly, not washing your hands and leaving the sheep carcass to decay is not just unpleasant, it’s adding to the chance of the draw coming up against you.
It’s sure not recommended. It is precisely on par with not washing your hands before preparing food, and for exactly the same reasons. It’s not that human hands or chunks of yesterday’s meals are deadly in themselves, it’s that they represent a source by which nasty bacteria can get into food, where it can then grow and cause seriously unpleasant illness if the food is left to stand for any period of time.