The New Décor and Ernesto Neto

There's little more frustrating than a wobbly table, the light that never comes on, or the couch that just isn't comfortable. In an artist's hands, however, such piffling domestic snags can be magnified out of all proportion, morphing into the bed lined with barbed wire, the chair shattered by a meteorite or the wardrobe filled with concrete. When interiors go bad, they can be genuinely disabling, maddening spaces.

The Hayward's ground floor is currently home to just under 80 of the most dysfunctional and downright evil objects imaginable, presented as 'The New Décor', which is also the last in three summers' worth of interactive fun-house shows on the South Bank that began in 2008 with the unsettling architecture of 'Psycho Buildings' and continued with the all-encompassing brainscapes of 'Walking in My Mind'. This being another contemporary group affair, there's none of the historical baggage of the Barbican's superb 'Surreal House', but then there's little of the lighter touch of previous years to lift an oddly oppressive mood.

It begins buoyantly enough, with Franz West's phallic pink and pistachio 'sitting sculptures' and many other awkward seats made from teddy-bear butts, saggy foam or S&M chains and leather tassels. A typically brusque Sarah Lucas punctures her sordid sofa with a thrusting neon pole, while two breast-like bulbs light up in excitement. Elmgreen & Dragset are on comedic form too, with their busted clock, boy's-only bunk beds and intertwined hand basins (entitled 'Marriage', despite being permanently installed in only the men's loo). Jim Lambie's disco-patterned floor and Haegue Yang's interconnected system of lights and blinds function as bursts of brightness, but there's plenty of shadow to balance this exuberance.

A coffee table by Rosemarie Trockel turns out to be closer to a coffin; a knackered kitchenette by Tatiana Trouvé feels like the scene of some fiendish minimalist torture. Yet, what's most cruel about 'The New Décor' is that very little of it is truly interactive. 'You can't sit on that', 'You can't photograph that', 'This one is being fixed' - are the viewer's constant entreaties and disclaimers. Accidents have meant having to remove or move objects, but ultimately these restrictions settle whatever doubts you may have had as to their hybrid furnisculptural nature: it's art and you can't (afford to) touch it.

The increasingly unattainable prices for contemporary art surely must mean that it's time for these touchy-feely shows to end, once and for all. Or is it? Because, upstairs is perhaps the most immersive, user-friendly experience going, created by Brazilian sensualist Ernesto Neto. Stepping into his sheer, multicoloured nylon encampment of tents, corridors and chill-out zones - grandly titled 'The Edges of the World' - is like getting lost at a festival only to find yourself on the set of a kids' TV show.

You can poke your head through the skin-tight stocking structures, smell the hanging tea bags filled with herbal concoctions and, if you happen to be wearing the right outfit, pop out for a swim on one of the terraces. But that's about it. There may be many ways to get in to Neto's work - it's social, interactive and optimistic - but I never get much out once I've left - any residual connection to the surrounding architecture or the city soon fades.

If the more pressing ideas about our relationship to domestic objects and spaces are downstairs in 'The New Décor', then they too are diluted somewhat by repetition: there's more Neto (a seating area, again not for public use), way too much Gelitin and an unwelcome return for Los Carpinteros - all of whom also appeared in 'Psycho Buildings' as well. Much of what's on display isn't too far removed from the designer furniture showroom, only Ugo Rondinone's giant medieval doors and Roman Signer's air-powered 'Floating Table' really stop you in your tracks or threaten to knock the stuffing out of the genre.

The New Décor and Ernesto Neto are at The Hayward until September 19 2010