Potassium argon dating labs
Sometimes the measurement is different than you expected, and the quote is probably about trying to figure out where exactly the disconnect is - is it with your sampling? It's certainly not the case in any literature I've read.
In most publications, scientists list all of the measurements that were made, including those that they ultimately left out of their data analysis, with detailed explanations as to why any dates were discarded - usually with fancy language like "we believe that the specimens may have been contaminated with modern organics during the chemical pretreatment stage", meaning "I'm pretty sure I dropped a hair in there." I've never read a paper that threw out more than 2 or 3 out of 40 dates, and I'm pretty sure that if you were tossing 8 out of 10 dates your paper would never get published in the first place.
However, the general principles involved in radiometric dating apply across methods.
Blind studies are employed to prevent bias in the results.
There is an aspect of the question that should be fairly easy to verify though.
The creationist website claims: No wonder radiometric dating labs require that all samples to be "dated" be identified as to their source in the Geological column!
No scientist I know has the kind of spare time or vindictiveness necessary to pull off that kind of thing. One of the times that it's done blind is in laboratory intercomparisons.Nevertheless it succeeds in doing for potassium-argon dating what Willard Libby's book Radiocarbon Dating did for that radioactive clock; it provides a balanced and sufficiently comprehensive introduction to the subject for the nonspecialist user of the data." It appears that this book is a very introductory text and the quote you present from the creationist website could very likely be a part of an introductory explanation of how K-Ar dates are done. If you pull it out of context, it can look incriminating, especially to the lay person, but it seems like a pretty basic statement: "if the data you got from the lab agrees with the data you have, then the data from the lab is probably good".This book is written for someone who has collected samples, sent them to a lab, received a report with the lab's measurements, and wants to interpret what they're seeing. As for the claim that eight out of ten samples are discarded, I couldn't find a citation for that in your source.In radiocarbon, for example, there have been several International Radiocarbon Intercomparisons.The most recent intercomparison, VIRI (Fifth International Radiocarbon Intercomparison), took place in 2010.