Do you consider localbitcoins decentralised?
Obviously no, since there's a centralized server (running in hetzner.de the last time I checked out) and there's a centralized reputation system which provides "trust" (running in the same server). Person to Person btc exchange is a nice a idea, but needs proper decentralization. Hopefully Mr. Malmi will sort that out soon:
https://github.com/identifi/identifiThen we will have true P2P exchanges...
LBC provides a centralized feedback system, but users should really only use this for determining how likely it is that someone will show up to a trade. The same with listings.
When dealing with users via LBC, you should take the same precautions regardless of their feedback. It would be very difficult to create a marketplace that is truly decentralized in all aspects.