The way the explain it is with facts, such as water damage or exposure causing objects to date thousands of years older than the really are. This then implies, to me at least that, you must choose between believing or not with no reliable proof of either one.
The following is taken from a wiki page about carbon dating, and yes I know wiki isn't the best source of information; however, there are many other credible references to establish the effects water has on the objects being dated. So the conundrum becomes, if there was a flood, nothing pre-flood would date properly.
Other effects
If the carbon in freshwater is partly acquired from aged carbon, such as rocks, then the result will be a reduction in the 14
C
C/12
C
C ratio in the water. For example, rivers that pass over limestone, which is mostly composed of calcium carbonate, will acquire carbonate ions. Similarly, groundwater can contain carbon derived from the rocks through which it has passed. These rocks are usually so old that they no longer contain any measurable 14
C
C, so this carbon lowers the 14
C
C/12
C
C ratio of the water it enters, which can lead to apparent ages of thousands of years for both the affected water and the plants and freshwater organisms that live in it.[12] This is known as the hard water effect, because it is often associated with calcium ions, which are characteristic of hard water; however, there can be other sources of carbon that have the same effect, such as humus.[19] The effect is very variable and there is no general offset that can be applied; the usual way to determine the size of the effect is to measure the apparent age offset of a modern sample.[19]
Volcanic eruptions eject large amounts of carbon into the air. The carbon is of geological origin and has no detectable 14
C
C, so the 14
C
C/12
C
C ratio in the vicinity of the volcano is depressed relative to surrounding areas. Dormant volcanoes can also emit aged carbon. Plants that photosynthesize this carbon also have lower 14
C
C/12
C ratios: for example, plants on the Greek island of Santorini, near the volcano, have apparent ages of up to a thousand years. These effects are hard to predict—the town of Akrotiri, on Santorini, was destroyed in a volcanic eruption thousands of years ago, but radiocarbon dates for objects recovered from the ruins of the town show surprisingly close agreement with dates derived from other means. If the dates for Akrotiri are confirmed, it would indicate that the volcanic effect in this case was minimal.[19]