The main problem with college games are the students in packs, most of whom would act like cowards if they were by themselves, and that goes for PSU students too. I've attended PSU games at OSU, Michigan, Pitt, as well as many other places, and always have worn PSU clothing. I honestly can say that the only time that anybody said anything negative to me was when an OSU co-ed taunted to me as I was leaving Ohio Stadium after the 1998 game; some Michigan frat guys jokingly said something to me when I walked past their house before the 2002 game but it was good-natured. Interestingly, I've never encountered any negative treatment when I've attended the Pitt games in Pittsburgh, possibly because I'm from here and know what areas to avoid. Moreover, when I attend games at OSU, I always attend the Skull Session at St. John's Arena, and nobody ever has said a negative word to me.
I've also attended two Steelers games in Cleveland (1993 when Eric Metcalf returned a punt for a td, and 1995 which was the last Steelers-Browns game in Cleveland before the Browns left) and wore PSU clothing rather than Steelers clothing, and nobody said anything to me.
I agree with you about also acting modestly when you go to an away venue. If you do that and hang around adults and children, especially if the game is during the day, you should be all right.