Plenty of people pretend to be but their aim is to divert you to a jewellery or a tailors shop where they earn commission added to anything you buy. The average tout is there to rip you off not provide a service. Better to go into the palace and there will be official guides in there who will actually know what they are talking about and speak English. Or you can do as most people do and just use the brochure sold at the entrance which describes all the statues, buildings , murals etc inside. Do not just go with some random guy driving a tuk tuk or hanging about in the street or you will get cheated.
Be aware of a scam that has been running for years were a very smartly dressed, official looking, man will tell you the Palace is closed that day and offer you an alternative guide round Bangkok
Thank you very much for your advices. Luckily we did not fall into the trap of those random “guides” along the streets near to the entrance!