No, it's not true. It's the biggest myth in onionland. Hidden services can supply malicious code just as easily as clearnet sites. Hidden services are not safer than clearnet sites. In fact, we're standing in the wreckage of the biggest attack on Tor users, and it happened from a hidden service! You should be *more* cautious when visiting hidden services, because the operators, or hackers who exploit the site, know that the users want to be anonymous for important reasons. Most clearnet sites don't give a shit who you are and they aren't interested in deanonymizing you. If you become a nuisance, they'll start using block lists of Tor exit nodes, problem solved on their end.