You can tell everything by observing a kiddush.
The people scarfing down herring and kichel are chassidish
The people with a cup of vodka in each hand are Lubavitch
The litvak is the one with cholent and kugel on his plate, but waiting for it to turn stone cold
The ungarish oiberlanders are the ones who have their kugel on fancy plates.
The unterlanders are licking the crumbs from the kichel off the table
If there are any sephardim, which would be unusual, they are the ones being served by their wives and/or children
The yekkes are the ones who are sitting at the table with one cookie
If I missed any groups that you need help identifying, just let me know. (I purposely left out one group because they are likely to start a flame war denouncing all rw jewry if I include them. They are very sensitive)