Hi Grammarian-bot,
I looked at the site you listed. Some of the words "look" singular but they are aggregatae and take a plural verb. There has been heated debate (twice!) on this site about whether "police" takes a plural or singular verb, but the site you referene shoes that police, like cattle, swine, clergy, etc., all take the plural verb.
I don't have a good way to help you identify which words are aggregate nouns - I wish I did, but I think you just have to learn them.
Can you be more specific about your questions regarding them?