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Just the other day I was watching a guy from afar at work. He was struggling with his stem and when he eventually came and asked for help I discovered he'd put a bolt in the steerer clamp from the wrong side and had kept horsing it up, eventually stripping the threads, because the stem wasn't getting tight.
He'd done this with an approx foot long torque wrench with a 5mm bit in it. I'm sure the leverage afforded to him by the torque wrench had contributed to his clusterfuck.
M_V
Kimmo
All this talk of torque wrench calibration reminds me of my attitude to their utility in a low-torque application like bikes - they're worse than useless to anyone with mechanical proficiency, unless you're just curious what they say and are going to use your own judgement anyway.
Aside from the user needing to rely on them being in calibration, a tool can't account for the degree of friction on the fastener. And using them precludes paying close attention to the feedback through a plain wrench and refining your own sense of appropriate force.
For a noob, the old joke about doing it up until it's stripped and then backing it off half a turn isn't just a laugh, it's actually good advice, in a way - it's worth deliberately doing that to some junk in order to get a feel for the scale of force applicable to fasteners of a given size.
When it comes to highly weight-optimised ally and carbon parts in particular, the acceptable window of torque can get pretty damn narrow, admittedly - but torque wrenches can be real trouble here, especially for inexperienced users, who I've seen complain a number of times that they broke something despite using a torque wrench.
The trick is to do the opposite of the joke; sneak up on it by shooting for the lower edge of the window and testing to see if it's tight enough. Obviously this can't apply to a splined interface, but they're usually more than beefy enough; with something like a seatpost or a bar clamp, it's much less carnage if it does slip - not ideal, but better than it happening during a ride, and probably worth it to refine your own sense of 'tight enough but not whoops I broke it'.
And of course, always use carbon paste on carbon parts; it dramatically reduces necessary clamping force. It's often handy on other stuff too, especially on glossy anodising - remember, that stuff is sapphire!