I enjoy helping when people come up to me with legitimate questions, for all the reasons you mention. It feels like half the time, I'm being bugged not for any real reason, but because the person couldn't bother to put some effort in first.

For example, I've become known as "the regex guy" at the office. I know regex really well as well as the ins and outs of the regex engines of languages we use. I don't mind when I get called over to help with a tough regex, or optimizing something. But way too often whatever I get interrupted and cross the building just to replace ".*" with ".+" or something equally simple.

I usually just type the solution and tell them my copy of Mastering Regular Expressions is on the office bookshelf if they'd like to borrow it, the first chapter should cover all the basics. I'm also very happy to explain the basics of regex to someone in my down time, but very few people have taken me up on that offer.