In an interview with Radio Times, WHO overlord Steven Moffat discusses his perceptions on the Doctor character, including an assertion that none of the Doctors yet seen are conventionally attractive. It’s an interesting read - you can find more details (some of which you may or may not agree with) HERE.
YahooUK also offers an interesting quote snippet from the same interview.
"He's not a human being, however much he larks around pretending he is," he continued. "He is different and it's time to stop play-acting. He's not apologising, he's not flirting with you - that's over."
Interesting. Personally, I think this avenue best suits Capaldi’s apparent style and attitude - and should serve as a welcome respite to the many viewers who grew fatigued by the ‘will they / won’t they’ undercurrent between the Doctor and his companions have shared for some time now (I never particularly minded this - but I know it does bother many viewers).