I never have till I moved to this small town.

On our court square the streets are lined with Shops that all or most have a second story.
Most of the second story units are low rent Apartments, but a few are Offices or other things that don't get much traffic.

One of them has a narrow entrance that leads up to an apartment or Office, it has a Plaque next to the door that just has an IOOF logo...
I've seen it around town and outside of town at a few places. One of is a grave yard. Another I think is some sort of Lodge.

One day, I googled it and it turns out they are they have a pretty long history in this town and way back other places as well..  Like old back into the 1800s or so.
Anyway I saw another post about Masons or relating to things Masonic and it reminded me of that.

I've never heard anyone mention it around here, makes me wonder what their story is and how many local members there are.

They were originally founded by a British alchemist who found cryptic scrolls in the desert.  Its mostly just drinking now, but some robes and Latin and shit.

I have a short story about IOOF.  I grew up in a small farming community in southern OK.  It was founded in the late 1800's, but when the railroad bypassed it by 2 miles in 1900-1905-ish, going to another town, the community I grew up in died long before I was born.  In the 1950's, a few old two story buildings were still standing in the old town square but dilapidated and abandoned.  One of the buildings had a IOOF sign at street level to a stairway going to an upstairs room.  I asked my dad what IOOF meant, he jokingly said "100 Fools".  Later he told me what it really meant and that it was a lodge of sorts.  He said when he grew up there (he was born there, at home, in 1918), that he prowled around in those empty buildings when he was young, meaning late 1920's, and in that upstairs IOOF room there was a casket with a skeleton in it.  The casket wasn't in the room in the late 1950's when I looked around, but it still spooked me a bit, until they demo'd all the buildings in the early 60's.

There was a IOOF in the town I grew up in, small mountain town. Most of the people in it were LEOS and lawyers and such.

There was a small 2nd story walk-up accessed by stairs on the side of a building in Dedham Mass that housed an IOOF lodge when I lived in that town in the 90's.  It looked like it had been there forever.

Sounds like the one I was trying to describe too..

What do they consider vices?

We have an Odd Fellows lodge in our town.
I've been to plenty of stag parties at it.
They also use it for voting day.

It's a fraternal lodge with funny hats.  They do charity and have a stated goal of elevating humanity.  There is some part of their ritual that involves a skeleton and a casket - but it's part of their history to bury the dead too (as a charitable act).