Whenever I see someone essentially say that they aren't going to evangelize to a person (preach about Jesus), but rather just express the love of Christ to the person, I end up interpreting that sentence in the following way:
"I, the Christian, am loving you in order to get something out of you."
Essentially, the love has an ulterior motive. The Christian is hoping that the way s/he lives their life, or interacts with unbelievers, will be done in such a way as to make the unbeliever want what the believer has.
I can't help but find that to be a manipulative motive for loving a person. The intention is to produce a very specific result: get the unbeliever interested enough to make the unbeliever convert.
I don't get the same reaction if someone says that they love humanity because God created people, or they love others because of how much God loved them, and so how can they not express that love to everyone else?
I'd even prefer in your face evangelizing to the "convert them through love" approach. At least the former is being forthwright about his/her intentions. And while I doubt that every single Christian who has done the latter approach sees it as a backdoor approach (or maybe they do), it's also incredibly ... it's almost deceptive, in a way. The Christian is still trying to convince the unbeliever to convert, on some level.