Is it just timing, marketing or gimmicks as with doge?
Yes correct, everything is about timing in the crypto world. There are also big hands in the game, that will ultimately determine coins that you find to be scam or shit, turns out to be one of the most profitable coins of the year.
Marketing has very little to do with how successful a crypto is, every shitICO with devs market their coin. The number one thing that determines value is community, and the reception of the coin. Even if a coin is a "sleeper" over years, if there is some support and the background of the coin is untainted, then it will have its time to shine at one point or another.
Almost every single crypto has a point in it's life, where it gets pumped for massive returns. Patience and research is required to find these gems.