I think in general motorcyclist are more courteous towards bicyclists than automobile drivers. You deal with a lot of the same garbage, motor or not, when on two wheels.
Although, I think there is a big exception to that rule--the "Sunny Sunday 'bikers'" Those are the guys, usually on Harley's, who's bikes will never even see clouds. They rarely wear any kind of gear, and are usually less than skilled riders.
Don't get me wrong, you will see these same types of riders on sport bikes, again, usually no riding gear (some say it is because of how expensive it is.... because stem cell skin revitalization is getting cheap these days).
Just like owning a bicycle doesn't make one a cyclist, owning a motorcycle does not make one a motorcyclist. Take it as an individual occasion--most riders wouldn't treat you like that. In fact, I know a lot of people who ride bicycles and motorcycles. I think if you are addicted to one, it is easy to become addicted to another.