Apart from the suffering opinion which has been beaten to death elsewhere on this forum here are a few common misconceptions.
1. Bonsai are a particular species of tree (often fed by the bonsai seeds that you can buy)
2. Those fake jade trees that you can buy are bonsai.
3. Bonsai make great centrepeices for the dining table.
4. Bonsai are actually starved to make them small.
Anyone heard any others?