In regards to the Tosti et al study #49:
"a brief, reliable questionnaire, was self-administered to 236 patients taking Propecia and 236 age-matched males attending the Department of Dermatology of the University of Bologna."
So you asked men to tattle on themselves if they Have ED. Not sure that could be entirely reliable.
Your link listed #34:
"Sexual AEs are reported in clinical trials at rates of 2.1% to 38%. The most common sexual AE is ED, followed by EjD and decreased libido. These effects occur early in therapy and attenuate over time. A proposed mechanism for sexual dysfunction involves decreased nitric oxide synthase activity due to decreased dihydrotestosterone."
- I'm sorry but looking at that link I see no mention of a placebo effect or anything about counseling in the use of finasteride, #34 discusses literature review
In study #41:
"One hundred seven patients completed the study. Group 2 patients (N = 55) reported a significant higher proportion of one or more sexual side effects as compared to group 1 (N = 52) (43.6% vs. 15.3%) (P = 0.03)."
-Now this is the study that discusses that almost double the number of reported sexual side effects from those who were counseled about those side effects.
However, you still have 15% of users mentioning sexual side effects who could not have been betrayed to a nocebo effect; they received no counseling.
#50 is your strongest study, another self administered questionnaire. I am impressed they had so low numbers in negative side effects in this one.
"We did not evaluate changes in the ejaculate volume in this study because this subject is not assessed by the questionnaire, although decrease in ejaculate volume is not rare in our experience." from study #50.