I think K/D says something about the caliber of player you are. But seriously, if you are above 1.0, you are fine. I don't care what my K/D is provided it stays above 1.0 (I think it is at about 1.5 now), and when I see a high K/D I don't automatically assume that that person is better than me at the game. I don't even factor it, really.
When K/D's get above 2.5 or so I usually assume there is some boosting going on. It's an easy statistic to distort.
It's also distorted by different approaches to free roam. Somebody who devotes all of their time on free roam to killing players, glitching into walls/bridges in order to make themselves unkillable (usually after they have a friend put a bounty on them), or using tanks is going to have a much higher K/D than somebody who doesn't like to get into tussles in free roam, and knows how to let things slide when some random kills them.
Seriously, people go to insane lengths to kill people in free roam. There was this one guy in a chrome Adder, chilling with a bounty on his head in the middle of the street, waiting for somebody to chase him (and watching the map carefully for people trying to sneak up off the radar). So I go after him assuming it is just a regular bounty, I'm off the radar, but he is still moving away. Eventually, he stops, and as I catch up to him I realize he crawled into his tank, which he eventually blew me up with.
Point is, it was a pretty clever move (although I would also say it is a bit cheap and meanspirited. I can't give too much credit to any kill from a tank), but what the f*ck did he gain from that? The guy waits in this one spot all day, watching the map, waiting for somebody to try to creep up on him, so he can attack them with his tank. It's a neat trick, but it doesn't seem like an optimal use of one's time.
And I know he does this all day because I ran into the same car, in the same spot, with the same bounty, heading toward the same route. This was hours and hours later, perhaps even a whole day. This is what this dude does for fun in this game.
Obviously, I quit pursuit the second time when I noticed it was the same guy. I'm not stupid enough to fall for the same trick twice. Not that I can't kill a tank (I'm very good at both going off the radar and attaching stickies to them, and I am also halfway decent at heavy sniping the driver from a distance), but I have much better things to do with my time. I've already proven to myself I can kill tanks, doing it again and again becomes redundant and expensive. Better just to let it go.
Anyways, the point of that /cool story was to illustrate just how far people go to get free roam kills, which can drastically raise your K/D ratio.
tl;dr: I honestly don't remember most of what I wrote about, I can't believe my post got this long. My tl;dr is that I am too lazy and my short term memory is too sh*tty to write out an actual tl;dr.