Lee Semel's answer in particular would make a great post here: a "to don't" list. You may wish to go through and identify the cognitive bias or biases each is an example of.
Thinking a little more, I think Joel Spolsky advocates selling to other businesses for much the same reason - they're fairly neglected and businesses are willing to pay a lot.
On Quora: What are some stupid things smart people do? Examples of common types of stupidity that are typical of otherwise very smart people.
Lee Semel's answer in particular would make a great post here: a "to don't" list. You may wish to go through and identify the cognitive bias or biases each is an example of.