Personally , I don't think there should be an ICO without whitepaper. The whitepaper bridges the gap between an investor and a company. Can we say a ICO without a whitepaper is a scam? Or what can you say about an ICO without whitepaper
Most probably around 99% of ICOs without whitepapers are scams. The remaining 1% are probably charity ICOs that just give away tokens for the lols. But based on experience, I find it accurate that ICOs without whitepapers are more likely to be scams.