Should I look at the client's code before quoting a value price?

No.

• It opens you up to risk from a total stranger
• It implies that you're operating with a scope-based mindset and will end up pricing based on your perceived cost
• You can find out what you need to know in faster and safer ways... and if it blows up in your face anyway, you can refund their money on day 1 once you've seen the code.