I recommend for your stamp listings to describe the faults, if any, on the stamps, and to provide a scan of both sides. Collectors are generally very interested in knowing any problems with the stamp condition, whether it is easy or not to see in a scan. Catalog pricing is based on faultless condition for most issues and this will avoid many un-necessary returns.
Also, if people view your listings and observe that stamps generally have faults that are not described, they will expect that this is the case for all of your listings, and assume stamps have faults (which will detract from your sales on sound stamps!).