Ebay has revolved around feedback over since its beginning. Even today with new policy changes where sellers are unable to leave feedback for buyers its still a very important feature. Researching a seller (or buyers) feedback can reveal alot of things you might not see by opening up the first page of their feedback.
First, you can go to ebay.com and click on the advanced search options next to the main search bar. On the left navigation you can search by seller. Typing in the sellers user name will bring up their feedback.
One of the best tools is an off ebay site called toolhaus.org. You type in someones user name and it brings up all of their feedback for as long as they’ve been on ebay. Here you can really tell where the a certain company lacks attention. You might look up and see that 9 of the last 10 negatives came from no communication after the sale. If you were going to encounter any problems with a sale, toolhaus can allow you to see months worth of non-positive customers comments.
Useful Tip: For powersellers or high volume sellers, problems in operations are going to happen. But on ebay feedback can make or break you. Using one of these tools from time to time can help you see what types of problems are going unresolved and cause negative feedbacks. Some problems are bigger than others but all sellers should review their feedback every few weeks to see if any internal processes or changes could result in less negative comments.