Professionally, I have found that Socrates was a good master - question something until it breaks down.
You know how sometimes it's good to notice changes in someone's figure. The words "You've lost weight, haven't you?" have come from my lips on more than one occasion - I tend to notice these things - and are always received well. However, it doesn't work the other way. Here's what I'd like to say to one of the workers from the next door office, but I always stop myself:
Hey - you're getting progressively fatter aren't you? It's gradual, but it's noticeable isn't it? You're turning into a bit of a chubber really, aren't you? - you looked a lot better when you were thinner. Add to that the fact that you're frequently found smoking outside of the front of the office... well, it can't be good for you. Give up the cigarettes... and the chips!
Pot, kettle, black...