Like with all other lore, there are different and conflicting ideas about what reptilians are like, but I tried to use the most common ideas here. To some they are horrible evil pedophile murderers and to others they are like humans with different personalities and agendas.
And of course they can take the appearance of humans, but how varies. Some say they can shapeshift, others that they wear suits, and yet others that it’s an illusion. Take your pick.