There isn’t much to “Scary Movie 4.” The best thing you can say about it is that it doesn’t have a great deal in common with the first two installments, which were devised by the Wayans brothers and were a grab-bag of crude, raunchy, extremely stupid gags based on teen horror flicks. Instead, like its 2003 predecessor, it’s directed by David Zucker, of “Airplane” fame; features Anna Faris, Regina Hall, Leslie Nielsen and Anthony Anderson in major roles (with Charlie Sheen and Simon Rex is smaller ones); and is structured as an interlocking take-off on some of the more recent big horror flicks. In this case it’s basically a spoof of “The War of the Worlds,” “The Grudge,” “The Village” and “Saw” all joined together, with other material arbitrarily tossed into the mix–most notably a send-up of “Brokeback Mountain” (pretty lame) and another on “Million Dollar Baby” (equally weak), a running joke about the clueless president (clearly aimed at Mr. Bush), and a concluding riff on Tom Cruise’s embarrassingly overwrought appearance on the Oprah show. Lots of sexually-oriented stuff is gratuitously added, especially at the beginning in a sequence featuring Charlie Sheen and a bottle of Viagra, but it’s interspersed throughout as well, and there’s a substantial amount of strategically-placed nudity, too. That’s no big problem, save for the fact that a major example of it involves Nielsen, who’s easily the most withered specimen of naked humanity to grace the screen since Sir John Gielgud bared it all in “The Pillow Book.”

In addition to Sheen and George, other guest stars show up briefly as the gags are piled on–like Bill Pullman as the “father” figure in the “Village” spoof–but not always to best advantage (Michael Madsen has an especially painful few minutes as the Tim Robbins character from “World”). But the worst casting decision has Craig Bierko subbing for Tom Cruise. He’s one of those bland mid-level comics that always seem like they’re replacements for somebody better; just think of a new version of Alan Thicke. Nielsen is as game as ever, but he’s certainly gotten shriveled and stooped with encroaching age (as has Cloris Leachman, who plays a catatonic woman all too credibly), and Faris is even bubblier than Sarah Michelle Gellar was in the original “Grudge.” Production-wise, the picture looks more lavish than one might expect of a movie like this. Perhaps that’s to be explained by the fact that “Scary Movie 3” grossed over a hundred million bucks, easily outselling the second Wayans installment. There must be an audience out there for this sort of thing.

But though there are occasional chuckles here–I especially enjoyed the line “Why do none of us have dryers?” in the scene mimicking the one in Spielberg’s movie where all that laundry is flapping madly on clotheslines in the wind–the material is mostly mediocre and the mugging pretty grotesque, especially when non-actors like Dr. Phil McGraw and Shaquille O’Neal show up in the “Saw” prologue. If you remember the movie spoofs on the old Carol Burnett show, the stuff here is of a quality slightly inferior to that. The difference is that Burnett appeared on free TV, which was rather a fairer deal for the quality received. This picture isn’t the dismal mess that “Date Movie” was–though they both include an equally dreary Michael Jackson joke (could anything be more passe?), and it’s actually marginally preferable to its immediate predecessor (mostly because it seems slightly less crass–or am I just becoming inured?), but it’s nothing to write home about either.