Re-tipped Cartridges?

I have noticed that there are a fair number of what I consider to be fairly well regarded cartridges (I.e. Koetsu, Van Den Hul, Etc..) that have been re-tipped and then almost immediately gone up for sale, either here on Audiogon or on Ebay. These cartridges typically have very few hours on them (usually less than 10 hours or so), and are very reasonably priced, usually less than a used non-retipped version of the same cartridge.

I have only just gotten back into vinyl, and therefore wonder:

Are these re-tipped cartridges no longer as good as they were?

Have they changed their sound, so that while they may not be worse, they are just different?

Or have the owners just moved on to either a replacement or to their backup cartridge, and grew to like them better than the re-tipped cartridge?

At some point I am going to want to upgrade my cartridge (currently a Koetsu Black) and wonder if I am getting a bargin by getting a re-tipped cartridge or getting a second rate cartridge.

I particularly would like to hear from those who have had cartridges retipped, and have heard the sound both before as well as after the re-tipping.

Thanks for your input guys.