I call it energy vampirism, and it sucks. (Ha! I hadn't planned that pun, but we'll keep it).
I do pretty well with my virtual garlic and crosses these days, but sometimes they sneak up on you--just one more question, just one more piece of advice that won't be taken, just one more story, just one more near-miss...
And then I think of Satya--the Sanskrit word translates not only as truth, but as transparency. And I realize that when I ask, "what can I do for you?" or "how can I help?", then I'd better mean it--because those words are commitments, though we pass them off as casual. They are cosmic pacts and you will be held to them.
Instead, I say that I will hold them in my heart, but that this well needs time to refill, and that can only be accomplished in silence--mutually spent or in solitude, but silence nevertheless.
Keep an eye on your own well, pets, because once it's gone, you too will have to draw from someone else's.
Just make sure they are willing to share.