I think that if you're going to rate threads, rate them sparingly. If it becomes a gigantic, effortless gold generator the administration is going to catch wind of it and drop gold revenue from it to 0. Now that you've brought it up, they may do it anyway to ensure that people don't do it in the future.
Rate posts instead! That is awesome. Everyone should use reputation.
Even if I don't do it myself.
Edit: It seems as if Loco is aware that you can get gold by rating threads. Or, at least, it's listed in the "How to gain Gold" thread stickied in this forum. Perhaps there is a limitation on how many threads you can rate in a day? If not, it's still abuseable...