How to know a profile is fake?

I find it very difficult, there is a fine balance between scammers who do not take real effort to answer in conversations versus real persons who stay general with their answers as long as they have no base confidence in the person. Can be like a vicious circle… Some indicators of fake are clear: quickly ask for mobile phone nr/ whatsapp/ write in better english than me/ inconsistencies between the limited profile input and what thy tell in messages. What seems to be a pattern is that profiles with only limited description, partner search up to 99y age, no questions and answers and in average 3 pictures are scam. Any advise on how to deal with this fine balance?