Radiometric dating is like any other form of dating: it's not perfect. No dating method is.
In fact, radiometric dating can be compared to the 'dating' method of keeping a watch. Now, anybody can tell you that a watch is not a reliable way of keeping time, because there are myriad stories of watches running too fast or too slow, or stopping altogether.
And yet we can use watches to be very certain of the time by comparing our watch with the watches of others, and with clocks in the area. Even though each of these 'dating' methods require assumptions, we can be very certain of the correct time by correlating them together.
Similarly, radiometric dates can be trusted when they are correlated with other dates. Thus, in the Creationist model, not only must every single pre-historic dating method known to man universally and constantly give false dates, often off by orders of magnitude, but they must all also coincide with each other in such a way as to make it appear that the earth is billions of years old.
™ Version 4.2