I experiment a lot with food combinations, and I know enough about their chemistry to avoid the particularly terrible ones. However, I know too little about flavor extracts to apply the same logic.
Just as an example, I've noticed that orange and almond extracts used together give a strong unpleasant taste to the food.
In general, is this just unpleasant tasting or actually harmful? Are there particular combinations of extracts, with food or with other extracts, that I should avoid?