... Is there a distinctive sound that results as a consequence? I'd appreciate if someone could advise/describe what "symptoms" might suggest phase problems.
Hollow sound, particularly when they are panned together. Try this experiment.. http://gearslutz.com/board/showthread.php3?t=64780
But a little out of phase can be useable, or even part of the tone. I.e., in a multi-mic'd drum kit, all the drums are never completely in phase, but the choices, or compromises, are ones that still sound good.