In the season 1 episode "I've Got You Under My Skin", after Wesley has been stabbed with the cross while attempting to banish the Ethros demon, the demon presumably "skims the surface of Angel's mind" and quotes Doyle. Though in the Buffy episode "Earshot", Angel clearly states that Vampires cannot have there mind read as there thoughts and memories may be there but are just like a mirror and dont reflect to the views of mind readers.