A bass is a cold-blooded creature therefore the surrounding temps affect the biological processes of the fish. Basically this means that the fish digests slower and does not need to eat as much when the water is cold. When the water is in the high 70's and low 80's the fish will need to eat more to maintain body mass because the fish's metabolism is moving faster. With this in mind, I think people mix this up by saying bass want fast moving baits when it is hot. It does not necessarily mean this. If you equate a slow moving lure as food, the bass only needs to eat the lure once per day when the water is in the 40's, but will have to eat the lure maybe five times when the water is in the 80's. I do not think it dictates whether a bass will prefer a faster or slower lure, only how many times it will have to eat a slow or fast moving lure during the day.
Mike