What would your solution to the problem be?
If copy bots are going to copy no matter what you do, should be just give up on all attempts to create a market place in the virtual world?
Or, should we encourage legitimate use and discourage illegitimate use to the best of our abilities, and try and create a valid market place.
Saying: Because people will take stuff we therefore can't have a valid market place is like saying that people shoplift so we should never have any shops.
I, personally, believe we should be trying to move the real world economies towards post scarcity economies (we are in a scarcity economy where the rules of supply and demand is in effect - a post scarcity economy is one where it no longer applies). There are many cases where we are moving towards such a post scarcity economy (Google search, etc).
The trick to beating illegal copiers is not to fight directly against them. Legitimate businesses are legitimate because they agree to work by a set of rules, the illegal copiers don't have those restrictions and so they will be able to beat any attempt to stop them.
What you need is to provide something that can not be copied, and so can not be stolen by the illegal copiers. This is can be simply "Customer Service".
If you treat the product as a free product, but instead are charging the buyer for after sales service, then it doesn't matter if someone copies your stuff as they won't have access to your after sales services.
Of course, an online marketplace does not have such a simple solution as described above, but it does offer such services: Searching, Product and Merchant aggregation (this is also why Malls in real life are so successful too), Purchase histories and other sales statistics, and so on.
These are things that are not really feasible for someone who is copy botting to replicate, and add value to the items listed in a valid marketplace.
because an online marketplace is moving towards a post-scarcity economy, then the value of the items in the market place are not based on a limited supply and a large portion of the value is based on the services offered by the marketplace, then someone copying an item does not cause such a great effect as it would if the item was in a scarcity market (eg: shoplifting fruit from a fruit shop).
Also, if you think about it. There are many affordable (and even free) online merchant software available today. It would be possible for any merchant on one of the online virtual world marketplaces to set up their own online market.
The question you need to ask then, is: Why doesn't everyone do this?
There are two main reasons:
1) It is not a trivial thing to do. It is hard and requiers a bit of technical skill. However, this is not really a barrier as someone could create a "Template Style" system where it would become trivial to set it up (there already exist such systems for other products)
2) There is more value to be had by having an aggregated marketplace than a fractured market place. Having a few (so there is competition between marketplaces) online market places gives Merchants and Buyers an easy way to access the products they want. It saves them time and effort and increases the sales the merchant will make. It is therefore much more valuable for a merchant to list in a big marketplace than to set up their own private one.
As illegal copiers would not be able to list on the big Marketplaces without being found out, then this limits the size of the potential sales they can make. This is because the big market places add value, and it is this loss of value that causes them to have a lower "profit" from their activities.