of course a good investor will first do its own research (whitepaper, roadmap and etc), besides that what is your biggest motivation?
Besides of whitepaper and team members, you must need to know the legal factor of their company if they are really registered in their country where they operate their business, and most of all, make sure that they really have a product to show to their investors, if they have nothing to show, the probability of being a scam is big.
The factor about having nothing to show for before you invest in a coin can be really deceiving, while it is obvious that those that plan to scam their users have nothing to show for, there are many successful projects out there that started that way and yet they delivered a great product so to me the most important aspect of an ico are the developers and their dedication to make their project a success.