Spiders Robots and Web Crawlers oh my,,,what's the harm?

Aside from knowing if it's people visiting my store or robots, is there any reason to turn off spiders. Is it just the hit counter that gets turned off? I think I want spiders crawling around so that my part numbers get some hits.

Mybe I just don't understand what's being turned off,,

What setting are you referring to when "turning off spiders"?

While monitoring Who's Online, the setting simply changes from showing to not showing what spiders are present. I don't want to venture out on all the other possibilities without a little clarification of what is being looked at. Each individual setting has it's own meaning and result and that should be identified at the location of where the setting is modified. That said, custom coding or other plugins can modify the described system reaction which is why providing as much description of the situation as possible is important in obtaining/requesting help..

config | sessions | prevent spider sessions

mespe:

config | sessions | prevent spider sessions

Spiders should not be able to have a session

mespe:

config | sessions | prevent spider sessions

Spiders will still troll the site with this setting such that spiders are prevented from sessions. The significant difference is that a spider will not be "awarded" a zenID. The zenID is a session that if posted/shared/cached to a search engine could cause conflicts for those that visit following that link. Ie., if two people come to the site with the same zenID in their URL, then basically they will share each other's cart. A product added by one will be seen by the other as if in their own cart...

As Design75 said, spiders should not be able to have a session...

mespe:

config | sessions | prevent spider sessions
You should NOT be messing with ANY of the setting under Admin->Configuration->Sessions. The default settings should be just fine for 90% of all common server setups.