We know that ideas are not copyrightable (except for patent related issues), but expressions are (idea–expression dichotomy). However, after reading about clean room design, I got somewhat confused. Wikipedia states:
The term implies that the design team works in an environment that is "clean" or demonstrably uncontaminated by any knowledge of the proprietary techniques used by the competitor.
Typically, a clean-room design is done by having someone examine the system to be reimplemented and having this person write a specification. [...] The specification is then implemented by a team with no connection to the original examiners.
This description suggests that mere knowledge of copyrighted implementation details can become an issue. And therefore the clean room method was devised as a technique to circumvent this issue.
To me this implies that as soon as I read a programming book (with code samples) or open source code, my knowledge is contaminated or biased and the code that I write might infringe copyright. Is this true or did I misunderstand the clean room design principle?