It all depends on the situation. I wouldn't put exploiting in the same category like cheating. Exploiting is like bending the game to your liking via playing the game in a way it wasn't designed but usually with methods available for anyone. Easiest example would be using item codes in names (character, childs, animal) or using typos like wrong buy/sell prices (e.g. ducks, cookout kit, recently fixed in 1.5.2).
Cheating on the other hand often correspond with additional external tools or mods to modify the game. A modding example would be CJBItemSpawner, which lets you, as the name suggests, spawn any item in any quality and quantity to your inventory. Other example would be hacks or "trainers" to alter game states.
Using either exploits or cheats in a singleplayer game isn't wrong in any kind. Play the game like you want but be warned, it may ruin your game experience. However don't lie to someone about achievements, awards, etc. or pretend playing an unmodified game when you used cheats or exploits in any way. In a similar way cheating or exploiting in any form of multiplayer game, where it isn't cleary allowed (example would be Minecraft 2b2t anarchy server) is bad because you ruin other peoples game experience.