Follow the steps:
- Search for interface
- Order by best seller
Results:
Nr 1 is an item that does not have keyword in keywords or title, only in description.
I think it is a normal behavior but it doesn’t feel good
Sounds normal to me. Sorting by best seller is literally going to rank by what has sold most from your original search criteria (“interface”) and will therefore supercede any other (prior) search criteria. Even if “interface” is being gathered from the description. It’s simply showing that the original search criteria is looking at and taking into account the description (amongst other things).
yes but it isn’t relevant.
Sometimes when you are serching for something else and you change the order the results are not relevant anymore, and this can annoy the client.
Depends on what you are looking for and how you search for it. If you are looking for interface sounds only for example, then there are a couple of things you can do:
- Search for “interface sounds” instead of “interface”.
- On the left-hand side of the results page, limit your results to the Sounds category only.
- Sort by best sellers.
You will then get these results.
Will that concept (which you can tweak to your personal preference of course) help you better find/sort what you are looking for? Good luck either way! 
