Get real, medicine is a matter of life and death. Multilevel marketing is harmless if you're selling handicrafts, yeah then it's an immoral marketing technique. In medicine immoral marketing technique are prostitutions. Plural. Not an abstract noun, several counts of the transgression.
Like in Dr. Seuss, "One Fish Two Fish Red Fish Blue Fish":
One prostitution, two prostitutions...
And if google translate turns "técnicas inmorales de márketing" into "prostitution", general Artificial Intelligence is here. And don't think your English is that amazing, vaidhy.
prostitution (noun): 1. ... 2. the unworthy or corrupt use of one's talents for personal or financial gain. (credit: oxford dictionary of English)
I am somewhat surprised that someone did not think to look for an archaic or disused definition already...