Have you ever shopped for a recipe and discovered that you forgot an ingredient or two once you got home? If it's any consolation, it happens to the best. Or maybe you just can't find an ingredient you thought you had for a recipe you planned to make. Your immediate reaction might be to come up with a substitution, but that's not always the best idea. As Boot Camp recruits from Worst Cooks in America (Mondays at 9|8c) prove, some ingredients are not that easily exchangeable. Blue cheese for feta? Not really. Cilantro for parsley? It depends on the recipe (going for Mex-Ital?). Salt for sugar in a baked good? OK, it might have been an accident, but you can't serve that!

If there's one lesson to learn it's this: You've got to know your ingredients and understand them. Watch the video to see some of the ingredient-swap sins committed in Seasons 3 and 4 — and you'll know exactly when to point them out while watching the new season.

Watch the video above to relive some top moments and learn a lesson or two on why substituting ingredients is not always a bright idea. Next time you're following a recipe, don't get too creative — it might not end up tasting right.

Watch additional Skill Drills videos on the Worst Cooks in America page.