I've been told that many PhD students struggle with ethical dilemmas, especially when their supervisor/advisor gets involved. I wonder what those ethical issues are and how you've resolved them?
The most important thing I tell my students is honesty. I will ask them before starting to be honest with me and other aspects of the research:
Honesty in all scientific communications. Honestly report data, results, methods and procedures, and publication status. Do not fabricate, falsify, or misrepresent data.
I have not supervised PhD students, but I have had conversations with some whom I whose works I edited. Some of the issues include some supervisors seeking gratifications from their supervisees. Some students have actually given financial gratifications to their supervisors to avoid "undue delays." Many lecturers I know have turned down such gratifications and have been labelled by the students as "difficult." A student told me that her supervisor had requested to "take her out." Of course, she didn't want to hurt the fellow by saying no. Rather she sought to have another supervisor. Some supervisors insist they handle the data analysis for a fee, of course. On one of such occasions, no data was available to analyze, but the student still paid and got the result of "data analysis."
Hhhmmmm...I have commonly heard about PhD students forced to cover their supervisors' classes and office hours, so they end up spending way more time teaching then doing the research. Also, some supervisors will insist on co-authoring a paper with their student, even though the student has not asked to co-author a paper.
I think what a PhD student need to do from the outset is to understand the issues of dishonesty, various forms of plagiarism, and be determined not to be caught in the web of this criminality, and also be ready to be seen to add to knowledge genuinely.