In Yankee stadium, you're probably right...probably in Philly as well, but only because their fan base are cock sucking assholes.
I grew up a Braves fan. We sucked when I was a kid, but got on a very, very, very long streak winning something like 12 division titles in a row (until this year when the streak will finally end). There were always contingents of fans for the visiting teams and we embraced them. Anyone who will show up to support their team on the road is OK in my book.
Hell, I've seen the Braves play on the road plenty of times and gotten warm enough reception from the home team crowds...in Tampa, NY (@ Shea), Chicago, St. Louis, and San Fran. It's about a love of the game, not some bullshit "those out of towners shouldn't be celebrating my team's misfortune" jive.
BTW, St. Louis has the best fans in MLB....and the Mariners suck donkey schlong.