The limitations of radiometric dating can be split into two general categories, analytical limitations and natural limitations.
Analytical limitations encompass the limitations of the machinery that is being used to date a material.
Geochronologists do not claim that radiometric dating is foolproof (no scientific method is), but it does work reliably for most samples.
It is these highly consistent and reliable samples, rather than the tricky ones, that have to be falsified for "young Earth" theories to have any scientific plausibility, not to mention the need to falsify huge amounts of evidence from other techniques.
his document discusses the way radiometric dating and stratigraphic principles are used to establish the conventional geological time scale.
It is not about the theory behind radiometric dating methods, it is about their , and it therefore assumes the reader has some familiarity with the technique already (refer to "Other Sources" for more information).
These are often characterised as the norm, rather than the exception.
So you can never have perfect running conditions and certain parameters will change over time, this is just the nature of high-tech machinery.
For example, you may want to date a zircon crystal using a secondary ion microprobe (SIMS).
This technique bombards the sample, slowly drawing material out and then sending it through to an ion counter.
Answer 2: Yes, radiometric dating is a very accurate way to date the Earth.
We know it is accurate because radiometric dating is based on the radioactive decay of unstable isotopes.
This age is computed under the assumption that the parent substance (say, uranium) gradually decays to the daughter substance (say, lead), so the higher the ratio of lead to uranium, the older the rock must be.