Usually, I imagine as many words as it takes to get your point across 

But from a forum owner's perspective, I appreciate posters who give fuller, detailed responses.

I do not think 10 words is long enough to be considered a 'good post'

the sentence above is already more than 10 words but dont exactly say anything useful...  my average is probably 30-40 words per post, depending on the topic.

I do not go so much by words.  I think you should always have at least 2-3 sentences.  Of course some posts cannot be covered in just a few words.

I have 5 words a post, but 30 words a topic. I have a Forum Games section on my board that usually only requires one word to respond. Since there is only one word a post on average, the members post count does not increase.

My forums have word count protectors, that are different for each forum..

For example, my general discussion might require 10 words, to account for anti-spam, but if I have a market place / Auction lot, It may only be 1-3 words, if someone just wants to bid and post "10$"

Sometimes, I dont even see the point in them, because everyone has seen that if you need 10 words, and you only have 4, your post will look like this

"Haha yeah, me too!

This is for the spam filter, blah blah."

Eh, Im not a lengthy poster...as you will see from this post, but like everyone I dont watch the length. I say what needs to be said and thats all. No more no less.

I think this is the biggest drawback because we count words. If a word can convey your message then it is fine, On the other hand some topics need to write more than 500 words so we should go with the wind.