This almost seems like a model of the grammar issues mentioned by Robin...

Inside job!

I think the grammar language issues can be broken down into two subsections

1) Age/Education - categorised by "belthazor" above, missing capitalisation, missing apostrophes are key indicators, textspeak/l33tspeak are others.

2) English as a second language (perhaps modified by age) which I think would be categorised by the "tank in turmoil". This shows a good grasp of English but lack of experience in communicating with native speaksers. This has casused some sentence structuring issues and words replaced by similarly sounding words. For example "want should I do?" which does have punctuation but has "what" replaced by "want".

TL:DR I think "tank in turmoil" doesn't speak English natively so shouldn't be judged by that letter as it's better than anything most of us could do in foreign langauges

@Lee

The non-native grammar/spelling problems and the native-but-young/uneducated problems are, however, completely different. An ESL speaker is more prone to make word order, sentence structure and contraction mistakes, use odd words, misuse slang or miss certain connotations. We rarely make homonym mistakes because our learning process is intricately tied to the written word, not the spoken. The kind of mistakes in Turmoil's letter or the OP are a fairly good example of mistakes an ESL speaker would be unlikely to make. I'm not saying that Turmoil isn't also an ESL speaker, but the letter does indicate a young person rather than a non-anglophone person.