Hmmm.... I have an inkling of what this could be due to. I keep going back to the stereotype of black people drinking Kool Aid. But the truth is that, for many poor Black people, Kool Aid is one of the cheapest drinks around, so poor people of all races drink it a lot (they're not the only ones, but probably account for a large percentage of the profits made by that company). As for the sodas you mentioned, going back to the Kool Aid thing. If you're used to drinking fruit drinks, when you want a soda, it seems logical that you would be more into fruit flavored sodas.
User Detail :
Name : Kelly R., Gender : F, Sexual Orientation : Straight, Race : Black/African American, Religion : Catholic, Age : 25, City : St. Louis, State : MO Country : United States, Occupation : university instructor, Education level : Over 4 Years of College, Social class : Middle class,  I'm really not sure why we prefer those types of soft drinks, but your observation is very true.
User Detail :
Name : Omeece, Gender : F, Sexual Orientation : Straight, Race : Black/African American, Religion : Christian, Age : 25, City : Reno, State : NV Country : United States, Occupation : Technical Support, Education level : Technical School, Social class : Middle class,  The same reason i see everyday at lunch with out fail whites ordering diet drinks along with their greasy pizzas.
User Detail :
Name : alex, Gender : F, Race : *poweRpuFF greeN*, Age : 19, City : houston, State : TX Country : United States, Occupation : *maDsCienTist*,  I've noticed it here as well
User Detail :
Name : Christina32047, Sexual Orientation : Straight, Race : White/Caucasian, Religion : Baptist, Age : 21, City : Long Beach, State : CA Country : United States, Education level : 2 Years of College, Social class : Middle class,