They must be removed without residue or exchange.
Especially the Sony A58 has a display that can not be folded down to the camera.
When the camera store you have to constantly make sure that the shoulder strap or the like does not come to the display.
Once tracks are on display it's too late.
If the foil is damaged, replacement is not a problem as 6 pieces in Lieferumpfang already exist.
I use generally protectors in cameras, mobile phones and tablets.