I just love it I can't explain why though I feel like its a way of showing her and the abide she's gone trough for us fans and she still smiles for us cause this is suppose to be a fan dedication song but still ATTPOP could mean anything
The fake smiles is what she put on during the last shows of the BTW ball.. yea its a big smile but she's sort of rotting inside because of the pain, hence the bad teeth :P
And she always covered her eyes when she wanted to hide herself because she didn't feel good enough, hence her almost always wearing glasses in the beginning of her career.