It was ten minutes before the guests were supposed to show up for supper. I had the house cleaned, the food ready, and the table set with the good china. I walked into the dining room to find the cat, up on the table, licking the brand-new stick of butter. Did I mention it happened to be the last stick of butter we'd had in the refrigerator?
I tossed the cat outside, grabbed a sharp knife, neatly sliced off the cat-sampled top of the butter, and put the butter dish back on the table. Yes, I put butter on my mashed potatoes. And no, I never said a word about the minor cat-astrophe. If any of that evening's guests are reading this, please accept my belated apologies, and I only hope you don't know who you are.
For those of us who are neither Emily Post or Martha Stewart, the finer points of kitchen etiquette tend to be a mystery. I know the proper behavior expected of a guest when a meal isn't exactly to one's taste—you sample, smile, and wash it down with lots of water. Except, perhaps, in extreme cases, like the time my uncle stopped at the house of an elderly neighbor and was invited to stay for lunch. The bread seemed to have flecks of whole grain in it, or possibly raisins. A closer look, though, revealed that it was crawling with ants. The neighbor's eyesight wasn't the greatest, and he hadn't noticed. As I remember the story, my uncle brushed the ants off of his as best he could and ate his sandwich. And after that he made sure never to stop by at mealtime.
Maybe he should have said something. But how do you tell someone you've known since you were a child that he has ants in his sandwiches? Even Emily Post might have had a little trouble with that one.
While I've never served ant-flavored bread to anyone, as far as I know, I have pondered bread-related ethics questions. If one slice of bread has a moldy spot on it, do you toss that slice or ditch the whole loaf? If you burn one side of the toast, do you put the scraped side down and hope they won't notice it, or do you try to hide it with jelly and peanut butter? Maybe it's better just to avoid the whole issue and let people make their own toast.
I do have a clearer answer to another matter of kitchen protocol. Is it acceptable to feed leftovers to your guests? Absolutely, especially if you're creative enough as a cook to disguise them (the leftovers, not the guests) as something new. If you're not a creative cook, another approach is to be clear ahead of time that the menu is an "encore presentation."
In fact, leftovers can turn out to have unexpected benefits. I once invited friends over to eat leftover Thanksgiving turkey and to make pie out of some wrinkled apples. Only a few people were able to come, but one of them showed up early and stayed long enough that we eventually got married. It was probably safe to assume he didn't marry me for my cooking. We did, though, debate for years over which of us turned out to be the leftover turkey.
Practical Prairie Woman 
We look forward to your Friday columns and I am always amazed at how you can edit a funny column every week! While reading your last, I remember when our son Paul was about 3 years old. We had a darn poor kerosene stove at that time, bought it because of wartime shortages and there wasn’t much choice in good stuff. This contraption was wickless, and Ginny says it had two adjustments, off and high. We had a toaster, shaped like a kind of pyramid, where you could put four slices of bread on it and place it over the flame. As the control was practicaly non-existant, the toast usually burnt. Paul would ask, “Mama, is the toast burned and scraped?”
As for the moldy bread, you pick the moldy spots off and make the sandwiches anyway. I did learn a trick from one of the “church basement ladies” – she always turned the heels of the bread to the inside of the sandwich, so you couldn’t tell that you were getting it until you took a bite!