Just in case it ever comes to it I was wondering if I could get a reputation score lower than zero.
Nope, the minimum value is 1. If you lose rep (e.g. downvoted) when you are already at 1 then it has no effect.
This question is answered at Meta StackOverflow
The StackOverflow team believes that everybody's special in their own way and doesn't deserve to have a negative self-esteem (aka reputation).
Other reasons for this design decision could be:
- Reputation is stored as an unsigned integer (can't be negative)
- Having negative reputation could cause people to make new accounts to get out of it
Reputation has a floor of 1. it can never reach zero or a negative number.