For some reason, not sure why, whenever I am talking to a scammer online he refers to me as "sir" or "Dear".
A few more signs:
If they are trying to rush you into things, if they are trying to get the money ASAP and still have not figured out project details etc. Getting mad easily at questions you have is another one, they seem to get mad and sometimes even say "If you think I am scammer go away".
IDK I feel like it is quite easy to identify a scammer from someone who is professional and knows what he is talking about, just need to be logical and not rush into things with new people without getting all the details and researching his history a bit.