"I'll stick up for anyone that's a friend and I'll try and justify their actions if I believe them, but what Sam did was, frankly… unforgivable," Mike revealed on Wednesday night's show.
"He mentioned that he was the most honest person in the experiment.
“Look, I don't know what was going through his head. I want to say 'he's a great guy', and he is, but then there's that," he said, adding: "It's conflicting for me."
The electrician - who is dealing with relationship drama of his own - says he didn’t realise the extent of his dishonesty.
"I didn't understand the extent of it, we're watching this as you're seeing it, so I didn't see any of this.
“I was embroiled in my own controversy, so to see how it played out and some of the lies and the deceit was really disappointing."