Never heard of prostitutes though.
Those are women (or men) who sell their bodies.
I think many Africans are associated as drug dealers.
Esp. Nigerians, while many of course are involved in businesses dealing with jewelry, textiles or oil.
But I agree what
@dafluff states in his first response. Everything 'exotic' and foreign here is approached with laughter and staring.
And I heard a security guard mentioning a 'orang bule nigeria'. Wow, must have been an albino.
Society is full with racism, saying that it is more extreme in Indonesia is really pushing it. In Puerto Rico for instance, there was definitely a 'the darker you are, the less you are' approach. Colleagues of Spanish descent were more often (and questionably) selected for promotion. But in California or so, the positive discrimation got completely out of hand. If you are a female who is gay and colored and with a disability, you will never get fired, even if you screw up everything you do.
Having said that, even here there is quite some prejudice which can lead to discrimination of course. Javanese are backstabbers, Sundanese look good but are dirty, Chinese are rude, Ambonese are fighters and bone breakers, in Flores they only want to party, Manadonese girls are promiscuous, etc.
But also
within ethnic groups people discriminate; see for instance the negative connotations as the word HITACHI (used for dark colored Chinese, you can figure out the words used in the abbreviation) or even BENTENG (CINA), from the pasar area in Tangerang.