One side quest, "A Good Scrub," in *Kingdom Come: Deliverance 2* unlocks a series of bathhouse-related tasks, including a search for a flea-infested item. Here's how to find it for Betty.
Pick Up ‘A Good Scrub’
Speak to the innkeeper in Kuttenberg about work. This leads you to Betty, the bathhouse owner (located southeast in Kuttenberg). Accept her offer to find Matsek in Grund. Matsek is hesitant to be seen with the bathhouse employees, so discreetly escort the three girls waiting in the courtyard to the city with you.

Promote the Bathhouse
Help Betty advertise the bathhouse by shouting its praises at the grain market, horse market, vintners’ street, and merchants’ street. Remember, this must be done during the day.
Clean Up and Finish ‘A Good Scrub’
Clean the bathhouse before the alderman's inspection. Failure to do so quickly will result in the bathhouse's closure, preventing you from progressing to the "Ill Repute" quest.
Finding Fleas for ‘Ill Repute’
After a successful inspection, speak to Betty again. She'll mention the council's decision regarding the city's main bathhouse. To influence this decision, you must drive a competitor's customer (the councillor) away. Talk to Meaty Mary, Katcha, and Little Lida to learn the councillor's dislikes.
You'll need chamomile brew (to add to a wine cask on the second floor of the competing bathhouse), and information from Lida (requires giving her a noblewoman's dress). Alternatively, steal fragrant oils from a cabinet on the third floor.
Finally, Katcha mentions a past flea infestation. To find the flea-infested item, search the beggars' camp near Kuttenberg's east gate. Examine the sacks to locate a flea-infested blanket.

Place the fleas in Councillor Naaz's laundry basket (and a clean basket) in the same room where you placed the chamomile brew. Note: Completing one of these tasks is sufficient to drive the councillor away.
Kingdom Come: Deliverance 2 is available now on PlayStation, Xbox, and PC.