It is often claimed that cryptozoology is a pseudoscience. I have written on this topic before, but I feel the need to do so once more right now, as I have encountered arguments that have made me come to realize that it would be germane of me to do so.
First, we need to define "science" and "pseudoscience". Science is a means of obtaining information by formulating ideas called hypotheses, testing them to see whether or not they match the reality at hand, and keeping or discarding them based on how well they conform to the physical evidence at hand. This process should usually be able to be repeated by others. Pseudoscience is something that has a superficial veneer of being scientific, but does not meet the key criteria of being scientific. While it is still somewhat debated what those criteria are, the two dominant schools of thought are the logical positivist, or verificationist, philosophy of science, and the falsificationist philosophy of science, particularly the latter. Verificationism means that a hypothesis needs to be able to be proven, or verified, by obtaining sufficient evidence for it to be scientific, while falsificationism means that a hypothesis needs to be able to be disproven, or falsified, by obtaining sufficient evidence against it to be scientific.
Cryptozoological assertions meet both of those criteria. If I assert that "a large undiscovered hominoid species is inhabiting North America", this could potentially be verified by finding a body of this hypothetical unknown hominoid. Meanwhile, it could also potentially be falsified by painstakingly searching every square centimeter of North America and failing to find one scrap of evidence, one measly little body part, to support the assertion.
There is the issue that many self-proclaimed cryptozoologists insert intrinsically unfalsifiable supernatural assertions into the field, such as asserting that a given cryptid is a noncorporeal entity, such as a ghost or a phantom. Indeed, critics of cryptozoology often use the ubiquity of such supernatural-seeming reports of cryptids in the archives of cryptozoology to imply that the cryptids in question are inherently connected to the supernatural, and, thus, it makes sense to lump in cryptozoology with the study of paranormal phenomena, such as parapsychology. Yet this is a grave error. This is because many known animals have been associated with supernatural phenomena, as well, just as frequently, if not more so, than cryptids. From superstitions of black cats being associated with bad luck to reports of spectral hounds to reports of cows being abducted by aliens, all of the same criticisms that are leveled at reported hypothetical unknown species investigated by cryptozoology could equally be applied to known species whose existence is unquestioned, and, thus, render the entire field of zoology pseudoscientific due to its association with the supernatural.
So cryptozoology deals in hypotheses that are potentially both verifiable and falsifiable, and the association of the reported creatures it investigates with the supernatural does not render it pseudoscientific any more so than the association of other, known animals with the supernatural renders "mainstream" zoology pseudoscientific.
One more argument commonly leveled in favor of classifying cryptozoology as a pseudoscience is that it has not had any successes thus far. While this statement is certainly questionable, and, indeed, I highly doubt its veracity and deem it untrue, even assuming that it was true, this would not render cryptozoology a pseudoscience any more than the fact that no extraterrestrial life has yet been discovered outside of Earth renders astrobiology (the study of life, including extraterrestrial life, throughout the Universe) a pseudoscience. Indeed, many of the same claims regarding cryptozoology being pseudoscientific could equally be applied to astrobiology. Yet astrobiology is widely recognized as a legitimate branch of biology, as opposed to a pseudoscience. So what gives? Why the apparent double standard here?
I honestly think the reason as to why cryptozoology is widely panned as pseudoscientific is because it has been marred by association with poorly-done versions of it that actually are pseudoscientific in the popular media. From true believers who fail to think critically and investigate what evidence they think they have managed to obtain to those who assert a supernatural origin for certain cryptids, it is true that most of what masquerades as cryptozoology to much of the population is, indeed, pseudoscience. Much of the real scientific work going on in cryptozoology -- such as the peer-reviewed articles in the Journal of Cryptozoology, the studies of potentially undiscovered large marine species by Naish, Shanahan, and Paxton et al., the studies of reported Yeti hairs that found them to belong to bears by Bryan Sykes, Karl Shuker's books, The Cryptozoologicon, etc. -- is obscure, and does not receive as much attention as the pseudoscience that surrounds it.
As cryptozoology is not, inherently, pseudoscientific, by bringing the actual science going on in it to the forefront and drawing more attention to it, hopefully, its reputation among the scientific community can be salvaged, and serious scientific investigations of reported cryptids can occur on a wider scale than they currently are.