Generally i've found they go pretty well if you have at least one person who can get the confused liberals going, preferably with a megaphone. I went on one that was the first protest in that city and it quickly turned it an occupation of the City Council Chamber. As for taking harry potter signs that sounds kind of fun, being a revolutionary doesn't mean being deadly serious about everything, sure capitalism is a horrific and exploitative system but humour can be a weapon against it as well as a way to help you endure. I'll not make the Emma Goldman quote because that gets gratuitous but you know which one i mean. Anyway conclusion is don't criticise people for having fun and do what you can to try and radicalise those around you.