It really bothers me to hear that; it's a common statement, but I think when you examine what it means to say a placebo is observed to be effective, it dissolves into logical incoherence. It's pretending that a lack of results is a result, that an unknown source of bias is understood through doubletalk/think. It's worse than homeopathy.
I find it quite frustrating that placebo can be observed to be effective in many scenarios but many scientist seem to dismiss it out of hand.