Honestly I don't feel comfortable complimenting guys on the size of their dick. Once I told a client I thought he had a big dick, because he really did, and he said ''you're saying this because I'm Asian right?''.. I was shocked... He took it the wrong way. I never said it again after that. Sometimes guys will tell me they think their dick is small, when it isn't true, and I don't feel super comfortable correcting them later. I don't really want to entertain this type of insecurity lol
However, if a man tells me he is worried about his physical appearance, I always take time to reassure him and sometimes we have a little conversation about beauty standards, which men are also affected by.