I think it should be up to the buyer to decide that. If a buyer is skeptical of a seller, then he should be the one to require it.
By the way, positive feedback is absolutely no guarantee of a good seller. It is very easy to fake a good feedback rating, as Audiogon (and Ebay for that matter) have no way of truly verifying that the buyer actually paid the seller any money. (Although, since Ebay takes a "cut" of the selling price, theirs is slightly better).
A better suggestion is that the seller should be required to give a phone number so that the buyer can speak with them directly, as opposed to only via email corespondance.
And as far as the poor English is concerned, I do not sweat that too much either. I work with enough foreign born "Americans", (not to mention that non-English speaking people also use Audiogon), that if their english is not perfect, I do not hold that against them. Having a good command of the english language does not preclude a person from being an audiophile.
These are my thoughts on the matter anyway.
PS Don't flame me for my poor grammatical sentence structuring and spelling errors. (I was born and raised in the USA, and I am an engineer, so naturally I couldn't spell my way past a 2nd grade spelling bee!)
