In a week when the chat show genre has totally and utterly consumed me, I have been thinking about who or what makes a good guest on radio or television.

Generally speaking, presenters like me work alongside researchers and producers who do what I call the 'heavy lifting'.

By this I mean that they come up with the idea for an item or a guest, they then track that person or those people (or 'their' people) down and then they conduct a pre-interview with this guest which allows for the wheat to be sorted from the chaff.

After all of this is done, a brief is prepared and that document lands on my desk in advance of the show. I will parse and analyse the brief and then proceed with the interview.

The beleaguered researcher will listen or watch that interview taking place and will subsequently tear their hair out with frustration at the bags I made of their hard work, or they will smile contentedly, knowing that all their hard work was delivered upon by the performing monkey who presents the show they are obliged to work on.

On both the shows I work on, there will be a lot of interviews with authors who, like film directors, actors and comedians, are not naturally born entertainers.

They are, for the most part, talented people who are forced by the nature of modern media to tour television and radio studios all over the world, telling the same stories over and over again in a bid to shift a few more copies in the given country they visit.

For the record, comedians are the most difficult of them all. They are notoriously melancholic/bad tempered and are generally very difficult to extract a fun interview out of.

A guy who goes out and does an amazing stand-up show for two hours could arrive into the radio studio and sit there with a morose head on him, in pain.

Thankfully, there are a few good ones who are genuinely happy and up for a laugh (Jason Byrne, PJ Gallagher, for example) but they are few and far between. The majority take life (and themselves) too seriously.

My friend Paddy kindly gave me a gift of a box set of interviews by Dick Cavett, an American chat show host who interviewed the great and the good throughout the 1970s.

Recently, I watched Cavett interview four directors in one go. Robert Altman, Mel Brooks, Peter Bogdanovich and Frank Capra were the guests on the show and it was extraordinary to watch each of these talented men deal in their own way with the spotlight upon them.

Altman simply didn't want to be there and the exchanges were excruciating. Brooks loved it and wouldn't shut up (thankfully, in this case, he was very funny). Capra was a gentleman (he was responsible for It's A Wonderful Life for God's sake!). I hit fast forward for Bogdanovich (sorry).

And then comes the third category which I reserve for those who write books. One of my all-time favourite guests on both radio and television was the late Frank McCourt.

We were two very different people from very different backgrounds and generations but as soon as we met, we hit it off.

He came into the radio show one morning to talk about his book, Teacher Man, and he noticed an apple on my desk. At the end of the piece, I said goodbye and was playing a commercial break when he reached across and took the apple.

I explained that I was meeting friends later that night in O'Donoghue's pub on Merrion Row. At 9pm that night, I was sitting with my back to the door when an arm reached around and a shiny red apple was placed beside my pint of Guinness.

The arm belonged to Frank and we sat, drinking a few pints until closing time.

He was a wonderful man, a joyous guest and had that irrepressible twinkle in his eye that can take an interview in any direction, which is unnerving and exciting at the same time. I'm only sorry that I won't have the chance to see him on the Late, Late Show.

In the past, I have been disappointed by authors I was looking forward to meeting. Lionel Shriver, who wrote We Need To Talk About Kevin -- a disturbing but absorbing fictional take on modern parenthood in America -- proved to be rather humourless (should I have been surprised?) and therefore a little disappointing.

John Banville was a pleasant surprise when he came in to talk about Benjamin Black, his pseudonymous alter ego. Esoteric with a twist of froth, I was glad to see that beneath Mr Banville's feline exterior lay a giddy Sopranos fan who probably needed a few nights on the lash.

John Connolly writes macabre and bloody thrillers and yet is one of the most affable, easy-going and refreshingly opinionated writers I have the pleasure to regularly interview.

Paul Howard is as funny off the page as he is on the page and I always like to see him coming into studio.

The same can be said of Cecelia Ahern who is much deeper and darker in 'real' life and has an infectious sense of humour that doesn't always come across on radio or television but may do so as she gets increasingly comfortable in a milieu she initially disliked.

British authors can be hard work (Zadie Smith was either tired or bored when we met) and this can be due to exhaustion.

They are assigned endless hours of interviews with all media over an intense few days, so when you are interview #234 on a call sheet, the author must dread the thought of giving yet another pen sketch of their latest tome.

As a presenter, I'd rather wait until the author was refreshed and up for a chat, rather than dragged by a well-intended publicist through the mire of interview #234.

Ryan Tubridy presents the Late Late Show every Friday night on RTE 1