The problem with dialects:
Dialect speaker usually do not speak their dialect when they are speaking with people from other area. The switch to the standard language with accent and some modifications related to the dialect.
I came from a dialect area speaking "itzgründisch". They have a lot of differences, and if you do not know the dialect, you will only understand parts of the contents.
There are differences in
grammar,
pronunciations,
words
There are vowel shifts. Hasen (rabbits) -> Hosen (trousers), Hosen (trousers) -> Husen, heißen (mean) -> haßen
Simple past is replaced by present perfect.
"Wo", spoken somehow like "wu" (English like woo) (where) is used in many nonstandard meanings. (It can refer as well to persons as to time, der Mann, wo hier war. 1954, wo ich in Frankreich gewesen war ... - this is wrong in standard German.)
A lot of endings are omitted.
Unfortunately, I cannot speak it very well anymore.
But when I moved to Dresden when I was three years old, nobody understood me.
A lot of words are different.
Zamet = Kartoffelbrei
Öwaschicharuhm = Kohlrabi
Millichstök = Löwenzahn
Schwammabrüh = Pilzsuppe
Gemää = Gemeindehaus
...
But when they speak to me now, they do not use the dialect. They use it when speaking to each other.
Source in the German Wikipedia
http://de.wikipedia.org/wiki/Itzgründisch
Wenn da kää Gald niä host, kaas da de fei nex gekeaf.
Umgesetzt in standarddeutsche Bezeichnungen (transformed to standard German words)
Wenn du kein Geld nicht hast, kannst du dir (gewiss) nichts kaufen.
Standarddeutsch: (standard German)
Wenn du kein Geld hast, kannst Du dir nichts kaufen.
(If you do not have money, you cannot buy anything.)
Note: For the most of the dialects, there is no standard of the written form. If you find written forms and read them, it does not sound like the dialect, because in the dialect, the vowels and consonants may sound very differnt to the standard. For example, "ä" and "e" may sound different in the dialect, but not in the standard language.
There was a standard for Low German some centuries ago, and they had a lot of own literature, but they changed to High German.