No one can be 100% trustworthy. I have seen vendors in Localbitcoins selling their old accounts to scammers and the latter using them to con unsuspecting users. EVen I had a few bad experiences with LBC, and my coins were returned only after I contacted the LBC admins. If you are talking about face-to-face transactions, then they are not only risky, but unsafe as well.
Yes, in-person = face-to-face. Never had a problem, know your surroundings, learn how to spot fakes, and if you live somewhere where violent crime is a concern be armed or bring an armed friend. I'd be more wary of receiving a bank transfer from a hijacked bank account and having my money frozen after releasing bitcoins to the fraudster.