If the function/method expects an int, string or complex type and I accidentally call it with the wrong type, resulting in an error, such as "can't add 1 to a string", or "can't access access that method because a string was passed".

>and what is good python vs bad python?

This is kinda of subjective but, for a start, don't just start at the type and do stuff until the bottom like a shell script. This is by far how I see most python scripts. All the other normal things. Don't repeat yourself (in moderation, a few times is OK). Keep it simple.