'Desperate' outdoes itself

It isn't unusual for a hit show to start coasting a bit by its fourth season.

American viewers, once they find a show, tend to stick with it out of habit — even when the quality dips. Hey, "ER" is still on the air in its 14th season.

And monster hits like "The Cosby Show" and "Seinfeld" were already on the downhill side of their quality curve by Season 4, although they remained highly successful through eight and nine seasons, respectively.

All of which makes "Desperate Housewives" stand out a bit in the television landscape. In its fourth year, the show is having arguably its best season ever.

Part of that may be due to the fact that the characters have been so firmly established now that there's almost a shorthand between the show and its viewers — we know these (fictional) people, we sort of know what to expect and we're rarely disappointed.

And knowing them so well, in an odd way, makes it easier for them to surprise us.

"Housewives" has always been full of great characters. The core cast has been reliably fantastic.

Outside the core has been sort of a mixed bag. There have been some additional characters that have worked well and some that have not (including the Applewhites in Season 2 and Ian Hainsworth in Season 3).

This season's big addition, Katherine Mayfair (Dana Delany), looks like the best addition ever. Delany is delicious, the character has integrated into storylines seamlessly, and The Big Mystery surrounding Elizabeth and her family is maddening fun to try to unravel.

And, week in and week out, "Desperate Housewives" remains a hoot. There's some very funny stuff in every episode. Even Susan (Teri Hatcher), whose shtick was wearing thin, was hilarious in the last episode as she tried to ingratiate herself with the new neighbors.

The show has always been funny. Even when the second season didn't live up to the first season, it was still funny.

The big improvement in "Desperate Housewives" has been the plotting. In past seasons, executive producer Marc Cherry and his team have been overwhelmed at times with all the loose ends. There are so many things going on that some storylines seemed to disappear for weeks on end. And the enormous cast of characters was going in so many different directions that they sometimes seemed to be in completely different shows.

This season, the comedy is still there, but the soap opera-like plotting has tightened up considerably. The separate plotlines and characters are tightly woven together — an amazing achievement.