Fake/Multipls I.D's

well its like if someone is saying i am offering this and this service i dont know if i can trust them because they just have like 2-3 posts. But they seem to be knowing what your interests are hence meanin they really could be one of the old members. So it makes you think why do they have to make a new i.d to promote something they are doing or services they are providing. Know what i mean!?!..