People like domain appraisals, ie. how much their domain is worth, undeveloped and developed.
There are so many factors, but the main ones are:
1. The amount of letters in the domain. Shorter the better as it's more memorable (about 10 and less).
2. TLD is an important factor, though is arguable as sites like delicious.com started as del.icio.us ie. ccTLD.
3. Keywords, so example: Fergal's BAF might be a long, long, long TLD, but it consists of memorable keywords: business, advice, forum.
4. Pronounceable or not. Very important in marketing. Examples like Google, and facebook are very easy to pronounce.
There are a few more, such as age, PR, but all sites start off as non-indexed, so to be fair, it shouldn't be included.
For a site to be marketable means to sell yourself; present yourself; make a mark in the Internet industry. Having a domain like oapdfok.com isn't as memorable, or impacting as facebook.com etc.
You need to look at if the domain is also brandable, which relates to marketability. Can your site impact others? Many years ago, Google was a random word, with absolutely no meaning. Now we say Google it, or go to Google, or Google PR etc. and we know what it is.
So, if we say AAM. Does the majority of Internet users know what we are referring to? I would say no. You need to get the word out, get your site out, let everyone know that AAM is the next big thing. That's what Larry Page and Sergey Brin did.
Again I say, this is all arguable. Everyone thinks slightly differently to the next and by the 100th person to pass their thoughts, though it may be similar to the person beside them, it will sure be different to the first person casting their thoughts. I only speak from what I see, so let it be 😉