Patients who fail an IVF cycle are extremely vulnerable. This failure is often the last straw, because they are not sure what to do next. They have no idea why the cycle failed, even though the doctor was so optimistic at the time of the transfer. They are usually completely in the dark as to what was done, because most IVF clinics are remarkably opaque. They do not share information with their patients, and the standard explanation is - It is our clinic policy to keep all IVF medical records for our files. Many feel quite hopeless, and this is why many go to another IVF clinic for a second opinion.
The new IVF doctor will often take advantage of their ignorance, depression and unhappiness. He will highlight all the tests which the earlier doctor didn't do, and say that the cycle failed because the earlier doctor was sloppy, and did not do the work up properly. He will then proceed to rectify the problem, by ordering lots of expensive and sophisticated tests. Some of these are so exotic that they are only done in a single laboratory in the world, and they will ask the patient to get this test done only in that lab. The fact that no other lab in the world offers that test should actually be a red flag - this means that the test is unproven and untested, and its clinical value is still controversial.
However, patients are naive and come to exactly the opposite conclusion, because they are naive. They interpret this behavior as suggesting that the new doctor has access to highly specialized technology which the earlier doctor was completely ignorant about - and this explains why the new doctor must be better! The new doctor is also happy to point out that one of the reasons the earlier cycle may have failed is because the first doctor didn't order this advanced test. However, now that the patient is in his safe hands, he'll be able to find out what the problem is, and fix it, thus increasing her chances of getting pregnant.
This sounds extremely logical, and patients are quite happy to do what the doctor says, without realizing that all these tests proven and haven't been validated. The number of tests is mind-boggling, and seems to increase year on year. This includes: sperm DNA fragmentation tests; immune tests, such as NK cells testing; endometrial TB PCR testing; and ERA (endometrial receptivity assay) testing.