Sometimes a person can have so much logic that common sense won't fit. Or common sense pushes in and logic has to pop right out. There just doesn't seem to be enough room for both at the same time.
It's like this: your friend always packs their shopping bags the wrong way. One day you explain the right way and are absolutely sure you were subtle, calm and kind and that no feelings were hurt. Except then your friend is all touchy about it and snappy and makes out they know how to pack their bags.
(obviously they didn't know or else you wouldn't have had to tell them)
((but now they do))
Feelings were apparently hurt because those bags had been packed wrong all this time, or because your friend has no idea how to take good advice or because, um, maybe they really loved that old way of packing bags? I don't know but feelings were hurt despite your best efforts to approach the subject in a good way.
That's logic and logic kicks you every time when it comes to other people. Logically, your friend should want to know how to pack their bags and should definitely want to know if they have been doing it the wrong way their whole adult life. Logically you have done a good thing in making sure they now have unsquashed bread and finally understand about cross-contamination.
Later, usually much later, in fact usually after consulting with someone else, you discover your friend was upset because you were critical of them in a public place, ie the checkout, and wouldn't take their hint to keep it down and because they didn't seem to be listening you raised your voice and did that thing where you make sure you get your message across no matter what.
Once this is explained common sense makes a brief stopover, just long enough for you to have that familiar sinking feeling but not long enough to make any real difference.
For a period of time after the event you recognise that your behaviour, meant to be so logical and helpful, actually upset/embarrassed/annoyed your friend to the extent that you are now having to seriously consider apologising for being so helpful (it is a truly crazy world).
The best you can now hope for is that next time common sense will step in first and stop you before you get to the stage of using The Voice or even just stop you from talking altogether. You vow never to offer advice again, even though this will mean leaving your friends and family in ignorance and under threat of mistakes you could help them avoid.
This promise to yourself lasts only as long as the sinking feeling and is soon replaced by the happy acceptance, vague, very non-specific, that next time will be different because you now know not to upset your friend in that way.
The next time you go shopping together (it may be a long time) you will remember not to tell them how to pack their bags and you may even notice their nervous glances as they wait for you to say something. You will also notice their meat is now separate from the other food but they still like squashed bread.
And you will be delighted to find you can restore their trust completely by explaining how online shopping works so that they never again need to worry about not being able to pack their bags.