Is Halal for me to work in a hotel which derives about 10 percent on its income from illicit sources? The case concerns a 5 star hotel which rents out accommodation and give food to tourists. However, a portion of these tourists consumes alcohol and other Haram food which represents around 10 percent of total revenue. Is it Halal to work in such a place as internal controller?

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Working at places of disobedience such as hotels that sell wine constitutes a serious evil, since most workers, in some way or another, commit what is Haram like forbidden glance or listening to music, etc..
So, it is difficult for a Muslim to be on guard against committing disobedience since such places are filled of tourists and wine is served there.
Then, one cannot separate himself from seeing unclothed women, hearing music, serving Haram food, managing customers' orders and so on, since all these actions and their likes constitute a form of co-operation in sin and aggression.
In addition, one who works in these places will become insensitive to sin or feel no shame of what is Haram because this becomes normal to him as times-passes and his continuous looking at it. Furthermore, one's bad inclination may overcome him and lead him to disobedience.
The Prophet (Sallallahu Alaihi wa Sallam) said: "Sins are Allah's Hima (i.e. private pasture) and whoever pastures (his sheep) near it, is likely to get in it at any moment" [Reported by Imam al-Bukhari ].
Therefore, we state that you have to avoid working in such places, and you have to know that if one gives up doing something for Allah's sake, He will grant him that which is better.
Allah knows best.