So I just read the wiki on vowel sounds (http://en.wikipedia.org/wiki/Phonological_history_of_English_low_back_vowels) and tried out saying some of those examples after looking at the citation of regional variances. Okay, so I "think" I say caught and cot the same...in listening to most people talk I would know what they are saying by context, not pronunciation. Ship and sheep, though, I don't think I've heard folks turn those into the same sound.
Having lived so many places I can usually pick out regions from speech, but not always.
Not having ever studied this, I don't think I ever realized how many technical variations there are in pronunciations and the little /o/ thingies to describe them. Amazing new world!

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