I've come across the following:
もらう (morau)
This is the last word we’re going to review. もらう (morau) means to receive or to get. This word has a nuance that you’re feeling grateful of what you’ve received. So you cannot use it for something that have negative nuance or about something that you don’t feel grateful about.
Recovered from crunchynihongo.com
Is this true? I can't find a reputable source which states the above. My book doesn't seem to mention this "nuance".