Warranties that are less than 5 years, there's no reason for limited warranties with speakers in a modern market.
Passive radiator and bass reflex ports in the same speaker cabinet - it's a recipe for bottom end disaster.
Two way speakers whose bass driver cone is wider than 200mm, you simply won't get the speed you need in the midrange.
Cables permanently attached through the rear panel, because this basically says I'm really an el cheapo product.
Speakers sold off the back of trucks because they are crap, with lousy sound, atrocious build and no after sales support.

Balanced sound: An even, balanced and sonically similar sound character from all five speakers in the home theatre system.
Clean bass: Bass sounds that have a definite sense of weight and believable impact without excessive boominess or a one-note quality.
Natural sound: Vocal sounds that appear to be honest and natural where females don't sound edgy or emaciated and males don't sound chesty or bloated.
Clear dialogue: Vocals, dialogue and other salient sounds that are clear and articulate during heavy action movie scenes.
Stable surround sound: Easily defined directional sounds that appear to travel past the physical boundaries of the speakers.

Switch off your amplifier or receiver when making or changing connections to prevent current surges from blowing your speakers.
Exercise caution when winding the volume up because distortion and clipping can easily damage your speakers.
Lower the volume when switching between components to prevent transient thumps from harming your speakers.
Keep your speakers away from corner positions otherwise bass will sound awful and performance well be severely compromised
Keep the bare tips of speaker leads separate when connecting otherwise you could short-out and damage your amplifier.