Many people enjoy TUMA because the anus and its surrounding tissues are rich in nerve endings that enjoy the oral stimulation. The taboo nature of the act also makes it exciting.
As a courtesy to the escort, people should shower thoroughly, paying extra attention to the anus and buttocks, before asking for TUMA. An enema is ideal, but failing this you can stick a wet finger into your anus to remove any fecal matter. Even after cleaning, infections and bacteria can be spread. Many escorts will prefer to use a dental dam. Shaving the anus will also make the experience more pleasurable for both parties.