As FDG-PET and FDG-PET/CT have gained acceptance, a number of beliefs regarding these techniques have become ingrained in clinicians; the time has come to challenge some of these beliefs, to better serve our patients and perhaps create room for novel ideas that may enhance metabolic imaging. Common beliefs that bear re-examination include: (1) The best radionuclide method to detect bone metastases is a conventional Tc-99m-MDP bone scan, because this scan visualizes the metabolism of bone, and bone metastases, by definition, go to bone, where they disrupt normal bone metabolism. (2) PET imaging is sensitive but far inferior to CT in terms of spatial resolution. PET can never expect to define tiny malignant lesions, 2-4 mm in diameter, surrounded by centimeters of soft tissue. (3) FDG-PET is superior to other imaging techniques for the detection of many solid tumors, but some tumors do not markedly accumulate FDG, and probably little can be done about that. Analysis indicates that none of these common beliefs are true.