I spend a couple months in Peru every year - never met one healer like what you describe.  I have only met the best and most caring people down there so far.

I do research who I am going to stay with beforehand though - no way I would sit with just anyone without having a referral first.  I always get a referral from at least one person I can trust and if there is info online about them I will check that too.  I also ask the healer a few questions beforehand - what is in the brew being the most important question, and then asking how their ceremonies are formatted ect....  If you keep these very easy guidelines then you are not likely to have any issues, and if you dont at least keep these easy guidelines then you are basically asking for trouble and kinda deserve what you get. 

Real easy to only stick with the good ones down there - there are so many good healers in Peru and it is super easy to get at least decent info about which ones are good online with even minimal research. I've sat with 7 different groups of healers and all were great - I knew they would be great before I even arrived because I did a little research before hand.