- Keyboard has poor key feel
- Keyboard has keys that do not type
- You hear plastic bits rattling inside of the keyboard
- Brown or black plastic pieces are falling out of the keyboard:
--photo of ^ here--
- Keyboard has keys whose key feel is different from other keys
- Keyboard has keys that occasionally do not type
- Has the keyboard been in a non climate-controlled environment for a long time?
- Has the keyboard been abused?
- How much has the keyboard been used?
- How hard do(es) the user(s) type on the keyboard?