Depends man... I encounter stuff like this all the time. Some times the bike lanes just full of gravel etc and we're all on the line, sometimes it's the fun time rider weaving all over as they learn to hold a line.. those ones I can usually spot and hang way back waiting for an opening in the actual road lanes and pass there as a vehicle.. if they hold a straight line and won't move right when I call passing, all bets are off and I'll do whatever I feel is safe/appropriate for the situation including passing on the right, I've only had one instance where the guy gave me attitude and with him.. reason wasn't gonna work. Do what you have to and treat them as obstacles rather then people if they aren't gonna work with you (that doesn't mean pass on the right unannounced.)