Student and model Sara urged the 20-year-old to be "honest" about his feelings for her, but Arron's comments led to her walking away from him.
However, Arron insisted that he wouldn't suit her, admitting: "Oh my God! Yeah, I think you're pretty hot and yeah I do fancy you a little bit, but smoking puts me right off you [and] drinking too much puts me right off you.
"I'm a bad lad, seriously. Sara, I'll say to you what I said to my last girlfriend. I'm bad news and I'm not the type of guy you want to go for, trust me."
Ashleigh Hughes and Shievonne Robinson had previously failed to encourage the pair to confess their feelings for each other.
Last Monday, Arron first opened up about his affection for the former Miss Edinburgh.
Big Brother's live Friday eviction will be screened tonight at 9pm on Channel 5.