Correct me if I am wrong, because I make this up as I go along.... I read a lot, but I drink a lot, too. Sometimes while racking from primary to secondary, I will take maybe 6 or 8 ounces of trub and put it in a glass and put plastic wrap over it while I am brewing another batch. Instead of pitching over a yeast cake, I want to clean out the bucket. The trub that I put in a glass has been in 5 or 6 % ABV wort for three weeks, and I don't sanitize anything. A couple hours later I pour the trub, along with my freshly hydrated yeast into the next batch and I get airlock activity in no time.
Sometimes if the trub is already 1" inch thick, I don't want to pitch over it and overfill my bucket. Sometimes the bucket stanks, and I just want to clean it. I feel like since the trub is already soaking in alcohol further sanitation of the glass is not necessary.