Not all Google autocomplete suggestions will be low competition, but some of them are new searches that the keyword tools haven't even picked up on yet. Some bloggers only use this as their main topic research strategy, so there's definitely some gold in the Google autocomplete suggestions. It's typically a manual process of going through each one that applies to your niche and checking to see if there's any competition. At least, that's what I do.

I don't know if that clears anything up or makes it more complicated. But I hope it helps.