Christine Churchill wrote a great article on SearchEngineLand recently titled When Ignorance Isn’t Bliss: What You Don’t Know About Your Web Site Can Hurt You. It’s a must for anyone that drives eBay traffic and sales via ecommerce Web sites… it’s also a general ecommerce must read.
Her point #3 about SSL certificates is crucial for larger operations that have had some employee turn-over.
Point #6 about IP address sharing and spam neighbors is also an important one.
Please share your comments and insights if you have additional information along these lines. Thanks.