I will tell you the truth. If the scam is good enough you won't be able to spot it that easily. There are however some clear indicators that we are dealing with fraudulent developers:
1. Unrealistic or hyper optimistic goals.
2. Stolen, copied whitepaper or paper without technical details.
3. No transparency, no real names behind the coin, no social media accounts, or fake LinkedIn profiles.
4. Self Moderated thread is usually slightly suspicious too, but that is rather minor fact, might be a way to deter idiots and trolls.
5. No real purpose, or project overly similar to already existing ones.
These are good suggestions but at the same time some of us are too lazy to check all those things you mentioned for example white paper even the one for bitcoin, I have not read as those things just bore me because of the technicals that are embedded in it.
With all other suggestions even some doing more by going to the extent of appointing reputable members of the forum as escrows or manager and the likes still end up scamming people of their resources.
For me, all the suggestions are only precautions and not a determinant. But some though are red flags