Employment law is very fact-based. Specific facts yield more specific answers and it's hard to tell from your facts.
Is your compensation similar to co-workers?
"Easy" versus "challenging"? Do you really want to approach your supervisor to tell him/her that you want easier work when you might be the only one they have who can get the tough jobs done? Less qualified people are usually the newer people. Are you sure that management is not pairing the newer workers with you so they develop your work ethic instead of that of the "slackers" you referred to?
Not legal advice / No lawyer/client relationship.
Not likely. What is "less desireable" is usually a matter of opinion. If you are in a bad situation, you should schedule a consultation with an employment lawyer to avoid having your complaining making things worse at work for you.
Essentially no one is going to be able to go through the facts and evidence of your case to demonstrate what proof they might offer and in what way they would do so on a website. That is why free consultations exist, because you are asking very astute questions that deserve answers before you hire an attorney.
This answer does not constitute legal advice and you should contact an attorney to confirm or research further any statements made in this answer. Any statements of fact or law I have made in this answer pertain solely to New York State and should not be relied upon in any way in any other jurisdiction. Additionally, we also encourage you to reach out to us via Twitter (https://twitter.com/#!/employattorney) or Facebook (http://www.facebook.com/WhiteRicottaandMarks) if you have follow up questions as we do not monitor questions after providing an initial answer.
If the employer is motivated by a discriminatory animus against you because of your race and is taking adverse actions against you because of your race, that is illegal. An adverse action has to be more of an annoyance or inconvenience. Do the less desirable jobs pay less? Do they put your safety in danger whereas the other jobs don't? If the less desirable jobs are just annoying, that may not be an adverse action in and of itself. If there are other ways the employer is mistreating you, the actions in totality could constitute a hostile work environment.
This answer is for general purposes only and does not establish an attorney-client relationship.