We took our bikes to Mackinac Island about 5-6 years ago; it was my wife, and our two kids. The ferry personnel were quite respectful of the bikes both loading and unloading, but just to make sure, I waited right near the ramp and when I saw them approaching our group of bikes (and mine in particular, since it's a Litespeed Ti MTN bike) I went right over and told the attendent that I'd take it from here. I think he was glad that I offered.
But I watched them load and unload all the other bikes, and I felt they did a very good job. There was no abuse whatsoever. I mean, really, just think about it; if they abused the customers equipment, they won't be on the job too long.