I agree that the label is unreliable e.g. if the provider posts available for the next six hours and then gets booked, they seldom take down the post (I do not recall noticing that ever being done) even though a good deal of that time they are not available and even after they have finished with the first client they may not wish to move on with a new one until a suitable refresher period has passed. But the original post asked if indicating availability at 2,3 or 4 am was a warning sign and I pose it is not in and of itself one.