What is the most common reason VCs say no?

The most common hidden reason is that the company does not look capable of producing a venture-scale outcome for that specific fund.

Does a VC no mean the startup is bad?

No. A VC no can mean wrong stage, wrong fund, wrong timing, weak proof, or a business that is good but not venture-scale.

Yes, but ask precisely. Ask which risk made the investment hard to underwrite rather than asking for broad feedback.

VCs usually say no when one part of the investment case breaks: market scale, proof, timing, round logic, investor fit, or internal conviction.