Acquiring complete detailed information about all the pros and cons of a product one might purchase would clearly be difficult and expensive  It is rational not to acquire such information unless one expects that the benefits of doing so will outweigh the cost and difficulty of doing so
Ttherefore, consumers who do not bother to acquire such information are thereby behaving rationally
Whenever it is rational not to acquire detailed information about a product, it would be irrational to bother to acquire such information.