I reached a similar conclusion about the bow that came with my cheap EV. It was synthetic hair.   This was before I purchased my FM Concert and two FM CF bows, but I did have a horse-hair bow belonging to my old Skylark.   

With the synth-hair bow that came with it - rosin built up on the EV strings and body - and I was repeatedly re-applying rosin and cleaning-down the strings and asking myself - am I applying too much ? but no - because the synth hair bow would eventually just slip, and glide over the strings... ( I was playing / messing-around a LOT in the beginning ).  Finally thought - try the Skylark bow - what a difference  !

At about that time, I got the FM Concert, and some weeks later got a second FM CF bow ( because - believe it or not - I dropped the skylark bow on the floor - RIGHT on the tip - and it broke !   It is beyond repair, but I keep it to mess with the "upside-down-bow" playing four notes at a time thing.....  (infrequently, and only when I need an excuse to do something insanely crazy...)

Anyway - long story short - I dumped the synthetic hair bow...  It will never see the light of day again....  

I suspect it has more to do with the synth hair than rosin type, temperature or humidity - of course you can "make it work" - but - WAYYYY too much effort for me to bother with @MrYikes ! LOL