I think you need to have a strong team to make your project attractive and trusted by investors. Without a solid team, your project will fail. I am not sure whether ICO will succeed when investors or Bounty hunters no longer trust ICO. Maybe you need with IEO but as I said, You must have a strong and solid team.
If an ICO project does not have a large partner and many people are interested in it, even if they run many marketing campaigns, that project cannot cause investors to change their minds because for them ICO is all scam projects.
you said if people are already interested on it . being interested means they wont think of that project as a scam .
there are people that still trust ico anyway .
marketing or large partner wont also be needed but what the project already have is enough knowing that people already discovered them and trust them .