It’s hard to be humble and cocky at the same time, but Robert Downey, Jr. does it very well. Looking quite dapper in a dark suit and rose-colored tie on a recent Dave Letterman show. Downey was self-deprecating, with comments such as “you’ve come along way, baby” referring to his opening of The New York Stock Exchange that morning, modest, telling Dave that getting back to the U.S. and especially his show was the hit of his publicity trip…and meaning it, and arrogant, describing how he repeatedly balled up the script pages of his new movie, Iron Man, and threw them against the wall.

Now don’t get me wrong, he was charming, using a large and small action figure of himself from the film to illustrate the difference in height between him and co-star Gwyneth Paltrow. Funny stuff.

In the end, his matter-of-fact persona and dry sense of humor drew Dave and the audience in and made him a good guest who interacted well with the host and ultimately, made for a good interview… ego not withstanding.

When something looks too good to be true… sometimes it just might be. Such is the case with Cindy McCain. She made a visit to Jay Leno’s show recently and appeared nearly perfect – pretty, well-put-together, forthright, humorous, a little overly controlled… and even willing and able to make fun of her Presidential candidate husband, John McCain, saying “he’s not a very good driver” and admitting that he lied about his age when he met her (he subtracted five years). Guess what? So did she (she added five). They didn’t find out until they applied for the marriage license.

McCain talked about her medical problems (prescription drug addiction, a stroke), being a pilot (she flew hubby in his first bid for the Senate) and a race car driver (drift cars with her son) and teaching special education. I bet she’s a gourmet chef, too.

She did achieve what, I think, she set out to – conveying how fit and young her husband really is — he’s going to hike the Grand Canyon again this summer, without her.

Interestingly, Leno was compelled to behave. He had a few mild zingers but, perhaps because she could be the next First Lady, he treated her with respect. And, in all fairness, she was, as Jay said, a “great guest.” Only time will tell if she’s the real thing.

Helen Hunt received a standing ovation when she joined Ellen DeGeneres on her talk show recently. Probably a good thing the audience gave it to her upon arrival. I won’t say she was bad, she wasn’t, but she just wasn’t great. She did take control and dominate the conversation (not always easy with Ellen)… which was ok. She did talk a lot about her new film, Then She found Me,… good. She even joked about her old boyfriend, Matthew Broderick, playing her husband in the new film… funny. And her timing and delivery are strong (she did win and Oscar, after all!). But something about her overall demeanor is plaintive and whiney and even a bit condescending. She always looked pained. It’s off-putting and makes for a less-than-satisfying experience. It may be what got her where she is in her career, but I wish she didn’t bring it with her to interviews… not good!

Watching Marisa Tomei on Conan O’Brien’s show was like being at Kitty Hawk with the Wright Brothers – you thought something good was going to happen, but it never really got off the ground. Not only did she dress in a nondescript frock, but the tone of the whole interview was, dare I say it, boring.

There to promote her new movie War Inc., Tomei actually spent more time talking about the film she’s making now with Micky Rourke, The Wrestler, in which she plays a stripper. Now, you would think, and hope, that would lead to some fun, provocative conversation… not so much. She did manage to laugh and giggle a lot (which is often all one can do when dealing with Conan O’Brien), but not much else. She didn’t even know what clip to set up.

It’s a shame, really, because you get the sense she has so much more to offer. Oh yes, she also plugged the play she’s currently doing on Broadway, Top Girls. Come to think of it, maybe she was just tired.

Kathy Griffin is an acquired taste and whether you like that taste or not, you have to give her credit for originality. Griffin’s recent visit to Craig Ferguson’s show was interesting because for a good part of it, she was interviewing him. Things started out normally – Craig asking her about a risqué clip he had just shown from her series My Life on the D List and Griffin explaining her way out of it…but then she turned the tables and started grilling Ferguson about his political hosting duties at the recent White House Correspondents Dinner. He seemed to eat it up. A good move for a guest to know her host’s situation and use it to engage him in conversation about himself. They kept pace with each other in a witty political discussion even mentioning his rival, Jay Leno, who told Ferguson that when he hosted the Dinner, George Bush “grabbed his ass.”

The discussion stayed humorously political and then Craig regained his host position as Griffin continued her gay-themed existence. They finished the interview talking about her visit to Walter Reed Hospital and the fact that her comedy is problematic there, although she did say they “have the sickest senses of humor” and loved taking off their legs to drink beer out them.

Griffin and Ferguson played very well off each other, listening and reacting beautifully. She was bubbly, funny…and crass, but she wouldn’t be Kathy Griffin if she weren’t.