TBH I think Messenger Plus deserves criticism for the "Sponsor Software". Messenger Plus is a brilliant application, and Patchou has done well to keep it fresh and up-to-date, and also his support in the forum is outstanding.
But there are other ways to make money, ie the store, maybe a donation service. Maybe you could go down the same road as redvsblue, who offer sponsors of the product something extra, maybe hold back release dates, and let sponsors have the program or test the new features first.
Anyway spyware/adware sucks, I think it’s a cheap way to make money relying on the ignorance of less experienced users. Also what it does to PC’s is terrible, and the 36 hour install who thought that little sod up!
So keep up the good work!