How do you identify a good altcoin?

I've been looking at altcoins for a while now and listening to numerous intelligent folks on how to identify the good ones, and now I'm asking for your opinions. Here are my thoughts and and some of the thoughts I've heard passed around.

1. Look at the team behind the coin: This one seems like the best of the ways to identify a good alt coin. In the case of the two best (imho), Bitcoin being built by the master himself Satoshi, and Ethereum being built by Vitak, these coins are my two big bets to stick around. They have the support, the exposure, the world tested experience, but mostly the brilliance of the original developers.

2. The Network effect, the longer a coin is in production the more people that come to believe in it, the more demand.

3. A working product. So many of these coins have shown only an Alpha and a whitepaper. Without a working product it's hard to gain my confidence. Once I see a working product I'm more apt to support the coin with my hard earned money.

4. Scarcity, if you have a billion coins it's going to take a long time before there is any true demand in proportion to supply. Many of these coins seem to create false demand by a small number of big coin owners not circulating their coins.

These are some of my initial thoughts, I'd love to hear yours.