This argument always seems to inevitably end up with people calling each other racist, but I don't see complaining about the rude behavior of tour groups as racist.
I think it's how one talks about it whether it's racist or not. If they are describing a specific situation with a group (like I encountered a group from x chanting in the park) I have no problem with the race being mentioned because it was an actual event and it can be used to understand a the situation.
On the other hand if someone is describing a general problem (like I hate groups chanting in the parks) I am more uncomfortable with it being narrowed down to a specific nationality/race because not only is that stereotyping that group and putting a bad mark on everyone that comes from that country even if some are perfectly polite but it's also something that <i>isn't</i> just happening with people from only one nation. While there may be a country that has more frequent offenders by saying something (like I hate x groups chanting in the park) does that mean that groups from the rest of the world are fine even if they are displaying the same behavior? I doubt that it what someone means but that's the connotation given when you specify a particular group when describing a general problem.