They still had to be a good dipiction Lofty as they'd also get in trouble for that too. They'd be accused of poking fun etc... Some of these royals are terribly sensitive about slights on their looks and even one done to make them look good could potentially irritate.
Same for poetry actually... Lord Rochester got in to an awful lot of trouble for his poem about the then king, (I think it was a Charles or an Edward but don't remember). Mind you, he was a rather naughty chappie so he probably deserved it!