Not a dumb question. DNS can be confusing even to professionals :)
If you have a domain at godaddy and your site is on wordpress.com, then you don't need a bluehost account (unless you're doing email hosting or have others sites there). If that's the case, then you should point your domain to wordpress.com and map the domain from there.
I'm not completely familiar with how wordpress.com does their domain mapping, but if you did have stuff on your bluehost account you wanted to keep, you could transfer the domain to bluehost, but its really up to you. Either way, if your site is being hosted at wordpress.com the domain ultimately needs to be pointed there.