When is my novel ready?

This post actually started as a reply to another post here: http://darkewhispers.blogspot.com/2011/09/why-good-review-of-bad-book-can-hurt.html  but became so long I figured it's better off in its own little corner of the cybersphere.  
What makes someone a writer? In my opinion not all that much. Cobble a few words together, have the desire, do it because you love it, and hey presto, a writer is born. 
But does that mean you should then give your story a quick once-over, checking for any obvious issues, give it a rudimentary cover, and send it out into the world? From what I've seen so far (to my dismay but not surprise), there's a lot... no wait... a LOT of junk out there saturating the ebook online shops (some shops are worse than others). When I say junk, I don't mean to be rude or sound superior, I just mean that sometimes great ideas have been sent out way too quickly, haven't been given the necessary time and vast attention to detail that a novel needs to make it really great. I'm talking about the re-writes (plural), the editing (plural), the sending out to third-party test-readers (not friends or family), the money or time or both spent on designing a really good, professional looking cover, the surprisingly complex task of setting the layout in print and ebooks, all of that. It seems crazy that someone would put the effort into writing an entire novel, even if many of them are short, and then throw it out there in its unfinished form.
It's a shame Smashwords, KDP, Createspace and the rest seem keen to make sure a book looks "good" without bothering about the written quality of the product within. (I use the term "good" lightly because there are still just so many obviously self-published badly cobbled together covers with poor layouts anyway). I know they can't read every book for quality, but there should be some form of audit, because currently there's nothing to separate the chaff. Sure, eventually a great book will do well on its own merit if it's been marketed well and has good reviews, it's just sad that so many readers might never read it because they're too busy drowning in the morass of bad novels to ever find your gem.  
It's tragic because It essentially means anyone with enough time to put enough words together (whether they make sense or not) and fashion some sort of cover, can publish. Which means they flood the market with rubbish and continue to give indie authors a bad name.
What's sad is that as long as people churn out poor quality books and the ebook shops accept them, that reputation isn't going to go anywhere. 
So if you've written a novel, fantastic. That in itself is a great achievement. Just make sure it's the best you can manage... and then leave it somewhere for a while and return to it with some objectivity and edit it... repeat... repeat if needed... make sure people with no connection to you love it... then make sure it looks professional... 
...and then feel good about sending it out into the world knowing you're contributing to positive change rather than negative stereotyping.