Last week, I had a really great conversation with one of my salespeople. We were talking about someone at one of our partner companies who frustrates the hell out of both of us because she thinks that a generous application of rapport-building will absolve her of all sins. She didn't turn in her bids on time? She'll call you darling and tell you how much she loves to work with you. She screwed up the entire two-thousand-line spreadsheet by reformatting it, making it impossible to upload EVEN THOUGH YOU TOLD HER SPECIFICALLY NOT TO DO THAT? She'll get on the phone with you and try to charm you into filling the spreadsheet in yourself while she tells you the numbers, and compliments your new hairstyle.
She's infuriating, and she's made the classic mistake of thinking rapport fixes everything. Any mistake, any failure to do her work, should be fixed with some charm and a little self-deprecating humor. But the truth of the matter is that while rapport is important, it is not some magical cure-all that covers up any and all failures to perform. And thinking that people will be so charmed by you that they'll never expect you to do actual work is a terrible mistake.
You see, people will forgive lots of things for a little while because they like you, but eventually, they'll get fed up and the charm stops working and becomes a part of the irritation they feel toward you. Co-workers will figure this out first, and start to resent the hell out of you for putting more work on their plates. Customers usually come second, and stop using you because you fail to meet their expectations, but might let you take them out to dinner or drinks a few more times first. And when your co-workers start protesting and your customers leave, your boss will have no choice but to address the issue. (Unless your boss is me, because I have ZERO patience for charming layabouts, and I address that crap up front.)
So, before applying rapport in a thick paste to every situation you find yourself in, ask first if you've done the work, met your obligations, and done what you said you were going to do. Because if you haven't, you are starting in the wrong place.