Posted By:
Dan BrettaRestoration can make some items more valuable depending on the lengths you have to go to to restore an item. Baseball gloves can be restrung, cleaned and oiled often making it more valuable. However putting a new decal on a faded or worn decal bat is not what I would consider acceptable. Cleaning up a bat though is acceptable as far as I am concerned.
It has always been acceptable to clean and restore 19th century photographs as far as I know...I'm sure Barry can chime in on that aspect of the hobby.