I have found that many companies that offer or require internal training activities (e.g. "corporate training" "in-services", etc.) request that employees fill out forms rating and/or otherwise providing feedback on the quality, relevance, utility, etc. of the training.

Several years ago, I had the "opportunity" to attend an internal training activity that was more or less a comedy of errors with malfunctioning equipment and an instructor that not only failed to prepare/set up for the class but lacked the competence and/or the motivation to actually deal with the problems. When this training ended, I duly gave a poor review on the official "anonymous" feedback form. Several days later, the instructor somehow found out and confronted me, telling me that I had violated an unwritten social rule that negative reviews were not allowed.

To what extent is it acceptable to give poor reviews to internal corporate training? For example, are there different rules for when the problem is the instructor's fault (e.g. did nothing but read slides verbatim, sexually harassed students, showed up drunk, bad body odor, did not understand material, illiterate, etc.) versus when the problem is related to systemic issues in the company (e.g. lack of management buy-in, training budget too low to adequately teach material, lack of relevance of curriculum to job functions, broken air conditioner, etc.)?

*Edit: If it was not clear, I am asking about providing honest, good faith feedback to people who might not want to hear it, not about providing distorted or libelous feedback to antagonize or victimize someone. For example, this could be something like, "It's not professional to make me sit in a room with an instructor who smells like rancid butter and who thinks his job is limited to reading the slides, expecially when it is not clear how understanding how to safely store firearms will help me since employees here aren't allowed to carry them anyway. D-, Would not recommend this training to others."*