Words in the wrong context

[ZenGum]

Don't misunderestimate yourself.

And youse guy's are really great.

I'm sure I could of thunk up more examples.

On this topic, I have been thinking about ZippyT's ... how can I put this ... unconventional approach to spelling. At first I dismissed this as the struggles of someone whose literacy level was sorely lacking (my apologies for this Zippy!) but I've been wondering, provided that there is a large enough group that take the same apporach, use the same spellings, etc, could we say Zippy is writing - CORRECTLY - in a dialect of English different from, eg, mine?

At what point does a local peculiarity become a legitimate regional dialect? And when or how does this become dominant?
For example, of course the correct spelling of words like colour and flavour involve the letter "u" ( ) but our American friends had to save ink (something about rationing during the war of independence, I think) and left the "u" out, to the point that this is now the (statistically) prevalent form. How many people need to agree on a non-standard usage or spelling for it to become an "accepted" variant? And then the "standard" form?