I have been thinking, that there really aren’t a lot of ways to actually have b’dieved tarfus in your kitchen, that someone needs to be concerned about.
We can safely assume that anyone who attempts to keep kosher only buys kosher food. Now, there are no companies who make questionable meat, if we assume they aren’t buying Hebrew National. There are some hashgachos I don’t eat, but what are the chances that they are serving you something from those, and that it actually is b’dieved not kosher.
You need to be concerned they don’t ask shailos when things happen. However, we can say that a shaila probably didn’t happen within 24 hours, and say stam keilim einum bnei yoman regarding these shailos, since it probably didn’t happen, and even if it did, it may be pogem b’ein. So I’m not concerned about keilim.
This thread raises an interesting issue of mleches shabbos. Yet, most things they would do are probably only bishul d’rabonon. I need to look into this again, but I’m not so sure you really need to worry about it so much if that’s the only ch’shash.
Hmmmm.