I concur with jvmacross and zard, the issue is the complete lack of ethics. Based on these sellers track record all they care about is making a profit, but at what cost? Re-sellers can do whatever they want, however, I find a certain balance in how one conducts their business is important. What some aforementioned sellers are doing is a preying on uninformed cel collectors.
On a personal note, I prefer to share my cel collecting experiences and MW, RS, AB, all serve as platforms to openly share information about cels, preservation, and concerns (scalpers or frauds). I find we should not discourage or remove the important cel practice involving discussion and sharing information. As a community we learn more from each other than alone. Lastly, many cel collectors are secretive or inactive in any social setting, so it is important to allow and encourage what little 'active sharing' that exists.