Most substitutions that are of the same food category are pretty decent. For example, yogurt instead of sour cream or buttermilk, soured milk (regular milk + lemon juice) instead of buttermilk, low fat milk instead of whole milk, milk and butter instead of half and half, etc.
There are some substitutions of dissimilar categories that work pretty well, such as apple sauce, tofu, or yogurt in place of vegetable oil in baked desserts.
There is a substitution, however, for lemon juice which calls for an equal amount of vinegar. I'm sure that the type of vinegar used impacts the taste quite a lot. I tried a more mild tasting vinegar (apple cider vinegar) as a substitute and well, the eggplant dip which relies on lemon juice to marry the flavors of the eggplant and tahini together came out tasting terrible.
Note to future self: do not use vinegar in place of lemon juice when making baba ganoush. Ugh, what a disaster.
