Harav Mordechai Druk Zatzal from
Yerushalaim once spoke about how it's hard to have Sinah that is Chinam - for no reason. If it's because I don't like a particular thing about you - that's not Chinam!
He said a pshat that I don't remember, and then he said a 2nd cute/funny pshat that of course I remember!
Very often Ballei Battim resent Talmidei Chachamim/Chasuvah people. They often end up feeling inadequate in their presence and internally it may bother them that they're not as learned. Such a sinah would not be Chinam - as crooked as it is, it's for a particular reason. However, sometime there's a person with a long beard and huge peyos, a frock, he shuckles Shmoneh Esrei for longer than everyone else, and appears to be a big talmid chochom - but in reality is a faker and trying to portray himself as someone he's not.
When the Baal Habos sees him and has Sinah toward him - it's Sinaas Chinam - because he's really not a talmid chochom!!!!