Two films had me gagging to flee the cinema this week: one because it was so distinctively unpleasant, the other because it was inept.

Unfortunately, they were both British, and both with high-profile signatures.

Ill Manors is pretty well made, with a well-orchestrated narrative and a strong sense of place. But despite the solemn self-importance conveyed by rapper-turned-director Ben Drew (aka Plan B), it feels like the latest example of what I've come to regard as "sink estate porn". Yes, we are back in the "manor" of Kidulthood and Adulthood, films which purport to speak with insider knowledge and sympathy for the lives of young people on London's impoverished working-class estates, but do so while seeming to relish behaviour that includes rape, murder and GBH to the English language.

Drew juggles a handful of story strands involving numerous drug dealers and the unlucky young women in their orbit, connected by a domino effect of violence and revenge. His own rapping narration fills in the background, suggesting that half of these characters are turned into monsters by their environment and, in particular, by a lack of family.

But like those other films mentioned, Ill Manors wants to have its cake and eat it, to moralise about the social conditions that create dealers and addicts, misogynists and killers, while indulging – one can only think for dramatic effect – in their macho posturing and vile behaviour; it's as if the filmmakers can imagine no other audience for their films than hoodies or lads (I certainly can't) and are playing to the crowd.

So having had to watch, in discomforting detail, as one of Drew's anti-heroes deals drugs, physically terrorises everyone around him and forcefully pimps a helpless crack addict (for no reason other than punishment for losing his mobile phone), we are then expected to celebrate his climactic redemption. The only consequence of such risible contrivance is an exceedingly bad taste in the mouth.

In contrast, A Fantastic Fear Of Everything is harmless, yet shockingly badly made. A so-called comedy, it stars Simon Pegg as a children's author whose attempt to move into crime fiction – in particular, his research into serial killers – leads to a nervous breakdown. His resulting paranoia, a fear of everything from bumps in the night to the simple task of doing his laundry, is played as an endless, stream-of-consciousness nightmare.

Writers in crisis can certainly be the stuff of comic drama; just think of the Coen brothers' brilliant Barton Fink. Sadly, this is in an altogether different league. The script is decidedly amateurish, involving characters who could have been lifted from naff TV sitcoms and overextended gags that might be enjoyed while under the influence but in the cold light of day make Mr Bean seem sophisticated.

I'm a huge fan of Pegg, who has made the transition from cult British TV to Hollywood blockbuster, via the seminal home-grown comedy horror Shaun Of The Dead, without losing any of his leftfield humour and charm. But this film feels like a misstep, a low-budget project that his popularity has helped to get made, but one in which enthusiasm has clearly clouded judgement. As a viewing experience it is many things – cringing, boring, lame – but never fantastic.