Not clustered yet not too plain, colourful but not rainbow, text is positioned correctly and not scattered or blocking the beautiful image, if it's animated... it should be at a decent speed and try to make it unique but doesn't have to be over the extreme animation.
Try using images that aren't seen very often, that usually catches one's eye easily.
Have the text to be small, not big or medium but small... but it's my personal favour only because I tend to be grabbed by the picture rather than the words. The text should also not be ugleh looking (meaning, it should blend well with the banner in font-style but not colour)
Stick with your "hot and hot, cold and cold" thing unless you can make things stand out more than the others properly and professionally.
No idea, this is just a rough view of what a good banner is to me. There's more to it, but I'm in a hurry to leave. Hope the information helps. (By the way, I can't see any images D: )