Yes, he can tell that Malgus absolutely despises him. It's easily made clear by the fact that he hasn't been killed yet.
"I can't tell you everything. He was my student for 12 years. He came to the Jedi late - very late - at ten years old. He was a slave before that. He has always felt things deeply. He is the most loyal person I have ever met. He is the best pilot and lightsaber duelist I have ever seen. He loves as deeply as he hates. He lacks impulse control and is arrogant. Had he gone to Sidious without first being dismembered and on fire, he would be better than his Master now. As it stands I've very little idea of how much he's lost, in either power or skills."
no subject
"I can't tell you everything. He was my student for 12 years. He came to the Jedi late - very late - at ten years old. He was a slave before that. He has always felt things deeply. He is the most loyal person I have ever met. He is the best pilot and lightsaber duelist I have ever seen. He loves as deeply as he hates. He lacks impulse control and is arrogant. Had he gone to Sidious without first being dismembered and on fire, he would be better than his Master now. As it stands I've very little idea of how much he's lost, in either power or skills."