How do you handle product descriptions. Is it necessary for us to write our own descriptions for each item instead of using the manufacturers description? Could this be causing a duplicate penalty?
It would help. Often the largest problem is if the product comes in multiple sizes... they tend to have the same description so adding a drop down menu (with the different sizes) can usually help in the situation.
How much variation is enough? Are we talking about moving paragraphs around or completely rewriting sentences?
I thing that rewriting should be fine , though some personal reviews might give it an original aspect.
What i found to be beneficial in avoiding duplicate content and just a better website overall, is writing a short, concise, but relevant description for each item. Then make a popup available when a visitors clicks on the more information button. You can put detailed specs and info on the popup. A lot of visitors already know what they are looking for anyway. For the ones that don't, a quick user initiated popup doesn't hurt, and the user never leaves the page. Obviously if you have 10,000 products this isn't going to work but for smaller catelogs it can be beneficial.