In my opinion this depends on the project itself and the idea behind it. Actually ICO's with low hard caps are kind of shady ICO's in my opinion, because they want to create hype around their ICO and then artificially drive price up because there was a low hardcap.
The idea of ICO's is to distribute tokens in a fair manner to the public by selling the tokens and raising money from that (crowdfunding). The ICO model is not intended to make a small circle of investors rich in a fast manner. Although unfortunately some people have forgot that and look at ICO's like at a quick money scheme.
An ICO with a solid idea will set a high hard cap for fair distribution and still be successful, just because the business idea will work and adoption and therefore demand for the coin / token will follow organically.
Those are my personal thoughts on ICO's.
I agree with this. Also, high or low really doesn't matter technically, it's more of a psychological factor. Low cap can mean that you only have a few devs who might get tired of the project and abandon it, but it also means higher potential growth if it succeeds. There's always a trade off. A coin can fail or be pumped and dumped even if it isn't intended to be a scam by the devs.