I have a few, on rotation:

"Does this *really* feel right, or am I shirking?" - you know, the rare occasions I write good code it's because I've made my judgements on aesthetic grounds, rather than by thinking it all through. I mean, the ability to think it through underpins the aesthetic; but in the end it's the unswerving adherence to an aesthetic that forces me to do the thinking through. And so often I think "(it's still a bit ugly but) that's good enough" when it really isn't.

I might boil this one down to "would I want CrazyTachTillyn to look at this?"

"What's the data structure?" Maybe it's because of the stuff I'm working on, but I find it cuts my work in half if I work out in advance whether I need to base my set of functions around a hash of arrays or an array of arrays of hashes or whatever.

"The system works" When something goes wrong it's very tempting to attribute this to some grand abstraction to do with Perl, my ISP or whatever. But that's a mistake. The error is always my fault; and believing this is a good thing because it puts the solution within my power. There IS an explanation: so I can find it out.

§ George Sherston