Should I Tell Boss What I Really Think?

Dear Experts, The internship was a very positive experience and I learned a great deal, but one of the employees nearly wrecked it for me. This particular employee works very hard and has some things going on at home, but is VERY difficult to work with. Without getting into too much detail, this person does not listen, gives very little work of value (while other employees have given me the chance to contribute, etc.), does not review my work, thank me for it or give me credit for it, and has me do a lot of dirty work. This person reasons they used to do the same type things during their internships, so it must be OK for me to do them too. Not only does this one co-worker treat me (and the other intern & administrative assistant) poorly, but many of the tactics they use seem averse to what I've learned from my boss, my schooling , and even on Twitter. I've refrained from saying anything because I've been able to find value elsewhere in the internship, feel funny assessing another professional when I'm an intern, and don't want to seem vindictive. If my boss asks me about my experience, am I better off just leaving this out? For me, it's water under the bridge and likely won't effect me in the future, but is it my duty as an employee to say something? My boss owns the business and it may help in future business decisions. In a more extreme scenario, I also don't want to be responsible for this employee losing a job. As you can see, from an ethics standpoint, I'm torn. I also don't want my boss to think that I'm the problem, resulting in potentially poor references in the future. Our Twitter Advice Project (T.A.P.) is no longer an active campaign. To find an answer to the above question, please use the "Search" box in the right-hand column of this website.