Of course, some things take on flavours if you leave them for a while but it’s less than you think and much less than we are led to believe. Marinate tofu for a lifetime and it will taste like tofu. Marinades can be affective at helping texture so for example a leg of lamb in yogurt (acid), wine (acid) or oil will help soften it and add a little bit of flavour but it’s not the main thing. If you are using it as a spiced coating or you’re using a flavoured rub, then you’re not usually getting that “into” the meat or whatever but making a nice tasty crust – great but just understand that’s all it’s really doing. Some things – salt, sugar, vinegar, even milk make a difference but that’s more about curing than marinating.