Nests and Masks

Thinking about a posting on Scott Maruna's BioFort blog, regarding the semantics involved in naming cryptids (and how we then perceive those mystery animals), it's probably worth restating the convoluted nature of cryptozoology.
Because cryptids are ethnozoological, their descriptions and names are based on intangible (unconfirmable) evidence. (What do I mean by ethnozoological? Cryptids are not part of a scientific hierarchy—instead, they take a place within a cultural folkloric classification, where perceptible similarities and differences are viewed from a localized perspective rather than a global systematic viewpoint.) So, cryptids cannot be completely described from the limited evidence available, and even should an unrecognized species be confirmed and described that matches most aspects of a reported cryptid, that discovery will not necessarily prove that any and all prior or post-discovery reports are of that new species.
In other words, a cryptid both nests, umbrella-fashion, multiple potential explanations (misidentification, mythology, unknown species, etc.) and masks itself in multiple identities (perceptions and descriptions vary with different individuals or cultures). Any of the nested explanations may, in certain situations, be correct, or may never be correct. Any perceived identity may correctly describe the mystery animal, or be close, or none of them may correctly describe it.
Unlike the Linnaean system of binomial nomenclature, where a species is named and stays in that position (or changes or is removed according to systematic rules), a cryptid has no strict parameters in classification. Bigfoot may be cultural myth, or the composite of multiple cultural myths; it may be the result of numerous misidentifications of known species; it may be the result of numerous deliberate hoaxes; it may be an unrecognized species of primate; it may be a composite of multiple species of unrecognized primates; it may be an amalgamation of any or all. Even nesting these explanations, Bigfoot does not present an explicit confirmable descriptive identity throughout North America. For some, it is mythical. For others, it is physical. Size varies; toes vary; color differs; stride, bulk, behavior, facial features may change from witness to witness. Any of these may be the "correct" characteristic if Bigfoot is a physical creature, but we have no reliable method for determining that, so the boundary of what "Bigfoot" is is nebulous. Some cryptids may even be noted with remarkably disjunct appearances from one individual to another. It is then part of an investigator's duty to determine what factors may influence perception.
This is one of the main obstacles in cryptozoology. I've seen investigators too quickly, or without enough evidence, focus on one particular explanation as the explanation. (And, once you have an explanation, any additional evidence can be manipulated into supporting it.) Sometimes, an investigator may focus too quickly on one particular identity (e.g., long-necks vs. elongated bodies). There are a few cases where an investigator, while claiming to present possible explanations, deliberately excludes those which don't meet personal preference. So be thoughtful—when you meet with theorizing, be careful before making conclusions. I'd rather see cryptozoology enthusiasts recognize that multiple explanations exist, and (moreso) why those explanations exist, without making unsupportable conclusions, than just jump on the latest speculations to be promoted over the Internet.