If you want to get a real-life granular picture of what can go wrong with algorithms, try searching for recipes. The search engines routinely ignore what you look for, insisting "Oh, this must be what you really want, because so many other people do." If you search for Spare ribs, worcestershire, mustard, garlic, onion, it will ignore the garlic and onion. There is even a chance it will ignore one of the first three - spare ribs, worcestershire, or mustard. If you double back and put the garlic first, it will ignore the mustard and onion. If you put the + sign in front of all of them it will go completely random, giving you chicken recipes and pork in general rather than spare ribs per se. And don't even ask about the sudden intrusion of paprika, mushrooms, and red wine, all of which are perfectly good ingredients for slow-cooker spare ribs, but I didn't ask for them.
When it does this to me and I see a recipe that I actually do find intriguing, I force myself to ignore it. I won't give the bastards the satisfaction. You got it wrong, dammit! I am giving you a failing grade for this assignment.