I just reviewed a great discussion on LinkedIn about Vendors & Planners and better way to interact. The common theme seemed to be communication is key! There were people from both sides who were passionate about this. The other common discussion was that errors and details seem to fall apart under the logistics and around money.
Some vendors (and some planners agreed) that planners can be cheap and try to get out of paying vendors for their full services. Some event planners felt that the contract from vendors were unclear and therefore it wasn't that they were trying to cheat the vendors but they didn't understand.
It's an interesting topic, really. For me I think that anyone in the business who is new is obviously going to have a learning curve, but any professional, regardless of their field, knows how to cover their ass. One commentator made an excellent point -- get a logistics list from your Vendor. As a vendor you should know if you need water, electricity, load-in space, who your crew will be, etc. This layout was great and not to far from what I do with checklists in my position. There's always the opportunity for improvement and there's also always room for mistakes. I think it's important to be recognize the potential for both but try to fix it before you break it.
In an earlier post I noted that you have to "know who you're working with." It's also important that you know what you're working with.