How can you tell when someone has low/fake self esteem? What are warning signs t!

Low self-esteem manifests itself through self deprecating behavior. Some of this behavior is more obvious than others. The only way to determine a person's level of self esteem is to have them tested clinically. Sometimes we confuuse it with simple shyness so it is important to determine the validity or the nature of the behavior.

Fake self-esteem is probably even more common but just as often not recognized. Fake self esteem manifests itself in people who tend to be very boastful, agressive. Oftentimes they are "bullies" who seem to delight in making others feel badly. Generally these types of people "seek out" others that they feel have low self-esteem as they see them as easy victims.

They look down while they're walking.
They're style changes every once in a while.
If female they wear a lot of make up.
When someone jokes about their looks they laugh but then get quiet and out of the conversation.
Either they wear too much clothes or not enough.
Too much clothes is trying to hide away, not enough is looking for the wrong attention.
Suddenly dressing in darker clothes so they can blend in.

Personal experience

they just act happy when they are not, they are inside nervous and want to run off someplace,
and not be where they are now, they just act happy and jello inside....