American? You mean what's widely available in USA?
Sweet/acidic 'mustard' just is not mustard. That is marketing BS, maube catered to youngsters who cannot yet handle spicy food? It is something else than mustard, containing a little bit of mustard, like mayonaisse does. A chararacteristic element of mustard is the fact it is spicy. Therefore, mustard is always spicy. If they specifically mention spicy, it is very spicy.
As long as I get real mustard when it looks like it (mentions mustard), and its mentioned when its spicy (read: more than normal mustard), I am happy. When I get that acidic/sweet crap I am not happy. Its easy to recognize though. The color is lighter than the real deal, and the structure is very creamy.
I just buy local mustard, Zaanse and Groninger. But the structure isn't creamy and you need to mix them before grabbing content else you end up with an acidic leftover in the bottle.