What are the hidden bonuses/penalties of hamlet stress buildings?

My source here states that there are possible side effects most often negative but a chance to be positive. The Activities wiki's are found here:

• Meditation
• Flagellate
• Pray
• Gamble
• Drink
• Visit the Brothel

A full list of Quirks can be found here.

And the Hamlet wiki is found here.

A list of possible negative and positive consequences after using the Tavern is listed on the Darkest Dungeon Wiki. The Abbey has a similar list. The Sanitarium however does not seem to have additional effects apart from the upgrades.

The positive and negative side effects of visiting a place are called quirks.

The Tavern and Abbey have positive and negative quirks that can be randomly gained by participating in the aforementioned areas. For example, by meditating, a hero could possibly achieve a Balanced quirk, which is a positive quirk that gives them +15% move resist. Likewise, however, they could also achieve a negative quirk from the same activity, such as Calm, a negative quirk gained by meditation that makes the hero deal -15% DMG on the first round.

To answer about the Sanitarium regarding quirks, no, you cannot receive positive nor negative quirks by visiting or interacting with the Sanitarium. However, you may use it to manage your quirks by removing the negative quirks and/or keeping the positive ones in exchange for payments of gold.

I hope these provided details are satisfactory. If not, please ask any questions and I'll do my best to answer right away.