The topic of race in america is a complex one. But our understanding of it evolves over time, just like in every other field of study. As a technical matter, the definition of racism is "prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one's own race is superior". That last part is important. Things can be racially motivated and negative without being racist. So for example, Indian person denied an apartment by a white landlord because "they make smelly food". Racist. Indian person refuses to rent to whites because he prefers someone who speaks his language. Racist? Depends. On the one hand, as a landlord he has the power to effect discrimination in a way that can cause a problem to applicants. But on the other hand, the language thing is about trying to solve a specific problem that he has, not because he thinks those people are inferior somehow. Similar situations, but the second is less racist than the first. Especially when you take into account the effect, which is that the Indian family being denied might have to work very hard to overcome this stereotype whereas the white family might well just move on to the next listing and be accepted quickly.
What you describe isn't racism at all - assuming, of course, that hte landlord would rent to whites if they spoke his language.
On the other hand, I'm pretty sure that Twitter would explode if a black candidate was denied for "speaking black" (personally, I find it hard to understand non-mainstream dialects of English). Although tecnically, that still wouldn't be racism, but rather just generic discrimination.
And strange smells coming out of the apartment are not specific problems. You are not entitled to having your culture or culinary tradition accepted or valued. Change the spices and it won't smell.
