To feel affection for the grade-Z science-fiction films of the Fifties, especially as their descendants get ever more deluxe, is perfectly natural and no cause for shame. (A Not-Guilty Pleasure.) To set out in the 21st Century to make a grade-Z science-fiction film of the Fifties, a purportedly shelved and now salvaged programmer named Alien Trespass, is another matter. It is, from whichever end you choose to look at it, the height of unambition or else depth of ambition, striving for badness, hiding behind badness, winking at badness, absolving badness.

Director R.W. Goodwin, a veteran of the X-Files series, does a decently good job of the badness, as well as a decently good job of suppressing his smirks over it. His cast, most notably Eric McCormack as the pipe-smoking scientist possessed by an invader from space and Jenni Baird as the plucky protofeminist coffee-shop waitress, play along with the gag and don’t give the game away. Some of the rear-screen projection and the indoor outdoor sets can arouse a genuine nostalgia for see-through studio fakery. The overall cleanliness and bloodlessness stay true to the period. And the image musters up a passable imitation of 1950s Technicolor, even though the use of color in that genre would tend to signal a grade-A production (The War of the Worlds, Forbidden Planet, This Island Earth, etc.), while the one-eyed bug-eyed monster and the “biogenic phase disrupter” (synonym for ray gun), among other special effects, are patently grade-Z.

At feature length, the joke inevitably wears thin, but it can be unexpectedly plumped up again at a moment’s notice, as when, for example, the townsfolk and the tentacled monster come together at a screening of The Blob at the local bijou. The joke there, or at least the funny part of the joke, is not that the movie-within-the-movie mirrors the movie-without (a monster amok at a movie theater); the joke, rather, is the attractive notion that anyone ever would have been moved to scream out loud at a thing like The Blob. You still might be better off watching The Blob itself or one of its actual contemporaries, wherein, for all the achieved badness, the filmmakers were trying their level best. That’s not only nobler; it’s funnier.

Monsters vs. Aliens, a machine-made cartoon from DreamWorks, credited to co-directors Rob Letterman and Conrad Vernon, is in some ways, but not in a budgetary way, not so different from Alien Trespass. It posits a secret government quarantine of benign monsters modelled on such Fifties archetypes as the aforesaid Blob, the four-fifths-human Fly (except now a Cockroach), Mothra, the 50-Foot Woman (a girl-power placebo), and perhaps, since I can’t be bothered to think of a closer approximation, the Creature from the Black Lagoon. Nor can I be bothered to contemplate the intentions and implications of the gung-ho military commander’s resemblance to caricatures of George W. Bush or of the evil alien invader’s resemblance to caricatures of Barack Obama. None of the figures, human or non-, merits a second glance as a work of graphic art. And the insufferable insouciance of the premise, fully and accurately summed up in the title, hides behind — instead of an alibi of badness — a smokescreen of computer wizardry, 3-D diversion, jaded in-jokes, capitalist confidence. Hides, but not successfully.

Sin Nombre concerns another kind of alien invader, the heartbreakingly lovely Honduran immigrant (Paulina Gaitan) who makes her perilous way, with father and uncle, through Mexico en route to Texas and New Jersey. Her path converges with that of a sensitive, pensive Mexican gangbanger (Edgar Flores), a teardrop tattoo by his right eye, who runs afoul of his blood brothers. First-time filmmaker Cary Koji Fukunaga offers a soft-hearted view of a hard world, seeking out tender innocence and then stomping it for our horror and pity. The illegal-alien film and the gang-life film are both genres that are prone to a certain sameness, and the combination of the two into one film doesn’t produce a sense of differentness so much as a doubled sameness. Slickly done, nonetheless.

The Haunting in Connecticut, about a bedevilled family housed in a converted funeral home, has the advantage of not being a remake of a horror film I refused to see in the first place: My Bloody Valentine, Friday the 13th, The Last House on the Left, a virtual trend. It also has the advantage of being a “true story,” thereby curtailing certain kinds and degrees of excess. Now, I realize it would be ruled irrelevant if I testified that I myself know a couple who live in a converted funeral home in New Mexico and who have had no experience of flickering lights, banging doors, charbroiled ghosts, or a malignant shower curtain. But then, these friends of mine, more than welcoming of manifestations, don’t have a teenage son on an experimental cancer drug that opens the gateway to another time, another dimension. There is, even so, a routineness and a staleness about all that; and in the direction of Peter Cornwell, there’s a compulsion to oversell it. The mass disentombment at the climax had no need to be oversold. Virginia Madsen, Martin Donovan, and Elias Koteas lend it some useless respectability.

I Love You, Man, co-written and directed by John Hamburg, demonstrating a better ear than eye, is a guy comedy with an original angle. A woman’s man with a well-developed feminine side suddenly feels the lack of a male comrade when the time comes to pick a best man, belatedly casting about for a buddy to cultivate. The lapses in taste — no, the eager, steady assaults on taste, the projectile vomit, the fart commentary, and so forth — lower expectations early on. But the personable Paul Rudd in the pivotal role has plenty of opportunity to show off his gifts, particularly in his forced efforts to be a guy’s guy, more particularly when inanely or inarticulately tongue-twisted, the urge to be witty running way ahead of the brain’s ability to come up with some wit. His spirited slippage into a Jamaican cadence is a crack-up. Jon Favreau does well, too, as a churlish noncontender for buddyhood. And, in the part of the leading contender, the least you can say for Jason Segel of Forgetting Sarah Marshall is that he keeps his pants on.