I totally agree that the cabin should be properly cleaned on turnaround, however its up to the CS how well it is done. In some cases (possibly in the one you mention) the a/c is late I/B and in order to save time a "pit stop" clean is done so that the aircraft is ready to depart on schedule. Not always the correct decision but I am sure you will appreciate the knock-on effect of missing a slot which can mean hours of sitting for another. Like I said not ideal but this is what happens.