"Code smells" are a well-known concept: they're things that make you worried your code is not of good quality, without necessarily being horribly bad in and of themsleves. Like a bad smell in a kitchen that looks clean.

I've lately been thinking of "architecture aromas", which indicate there might be something good about an architecture, but don't guarantee it.

An example: you can't think of any compontent that could be removed from an architecture without sacrificing main functionality.