Is radiometric dating this inaccurate?

Scientific accuracy is about known and to some extent unknown errors. The popular media will report that some object is 4000 years old. The actual scientific report says it's 4,010 years old plus or minus 200 years. If by some other method the object can be definitely dated at 3795 years old the scientific report is accurate. The errors are calculated by taking many measurements on known samples and calculating an error factor from them. Once you have done this a few dozen times you can predict what the errors will PROBABLY be, specially if you run two or three measurements on your sample. Another laboratory might report the same object as 3820 years old, plus or minus 300 years. Both reports are correct, because they overlap.

All science is the same, even down to measuring the amount of ash in a sample of coal, which might be reported as 7.46% plus or minus 0,02%.

By contrast there are a few supposed dates for creation calculated from the Bible. You have probably heard of Bishop Ussher's 4004BC. There are dozens of others, 5411BC, 3760BC and 5503BC and just some. These were supposedly calculated from evidence in the Old Testament by people who were all using the same text. There is a big difference between 3760 and 5503 compared to the numbers themselves. So these dates are not as precise as scientific dates.

Anyone can claim that a popularly reported date of 4010 years for an object known to be 3795 years old is wrong, but they either don't know what they are talking about or they're lying. In most cases it's the second.

If the age of a dinosaur bone is known to be less than 6000 years old radiometric dating is going to get it wrong every single time.

Sounds like a quote from a creationist website to me. Without knowing specifically what they are tallking about it's hard to respond, but my guess is that they have only given examples of things that are known to give incorrect 14C dates, such as living aquatic snails which absorb carbon from ancient sources. The key word there is "known".

Without any argument to back up that claim, and with the fact that radiocarbon dating does give sensible and consistent results most of the time, otherwise it would be useless to archaeologists, we can simply respond "no it isn't".

This link provides some instances of close corrlations between 14C date and actual date (scroll down about 2/3 of the page):

http://www.talkorigins.org/faqs/hovind/howgood-c14...

The statement is either badly mistaken through ignorance or plain dishonest. A third possibility is both ignorance and dishonesty. When carbon-dating, for example, can be compared with historical records with known dates (eg. with some artifacts from Ancient Egypt), then properly conducted datings on suitable objects are shown to be accurate.

Certainly not 100% unless you consider a discrepancy of one part per trillion significantly. Few of our tools are perfect and there is always unreasonable doubt. Neil