Leftover bait? What is that? I fish till the baits all gone, or the beer!
No, really, I would never eat it, that's gross, but what I like to do is experiment on a few bait recipes with it.
I sometimes will add garlic, strawberry jello, or anything else I think the fish will like, bacon grease is a good one. I then stick it in a jar, label it, and then put it in the fridge or freezer, depending on when I plan to use it. Sometimes, a day or so before fishing, I'll take it out of the freezer or fridge and let it sit in the hot sun for a day or two before using it. If this is the case, I always make a note of it.
Next I test it out, if it is effective I note the recipe in my journal, and weather or not I set in in the sun to rot first, and I also note what species it attracted and the body of water.
I know, I'm kinda anal about stuff, but I do catch lots of fish.