Critics disliked the film intensely. The Times review called it "one of the two most nauseous films ever made" and Christopher Tookey in the Daily Mail called it "the most shamefully inept, witless and repulsive British comedy that I have ever had the misfortune to see". Writer Will Self, writing for the Evening Standard, called it "mirthless, worthless, toothless, useless", while Johnny Vaughan in The Sun stated in his review: "The mind boggles as to how this movie actually got made." Kevin O'Sullivan in the Daily Mirror called it "one of the worst films ever made". Peter Bradshaw in The Guardian wrote, "it's a film which isn't in the slightest bit funny or sexy, and is deeply depressing. It also diminishes the reputation of many excellent TV comics, who are made to look tawdry and naff up there on the big screen in an echoing cinema". Catherine Shoard, in a review of the film in The Sunday Telegraph, stated "It's hard to know what to say to this – it's like finding the right words at a nasty accident... Sex Lives of the Potato Men is probably the lewdest Brit-com since Confessions of a Window Cleaner, and certainly the worst". Shoard also described the film as "Less a film than an appetite suppressant". Ben Davis in the Morning Star later included Sex Lives of the Potato Men on his list of "some of the year's worst films". One of the few positive reviews for Sex Lives of the Potato Men came from Mark Adams in the Sunday Mirror, who wrote that "Vegas and Crook are a sleazy dream-team and brilliantly cast as the soft-core spud men... After several pints and a curry it could be the lads' film of the year." It was also controversial in that nearly £1 million of public money from the National Lottery via the UK Film Council was used to fund the project. Nigel Andrews in the Financial Times criticised the use of lottery funding for the film. Years after the film was released, Sex Lives of the Potato Men was still being described by film critics as an unusually bad film. Hostile critics include Peter Bradshaw of The Guardian, and the BBC's Mark Kermode, who described the film as "absolutely, indescribably horrible, vulgar, stupid, tawdry, depressing, embarrassing, filthy, vile, stinky, repugnant, slimy, unclean, nasty, degenerative and mind-numbing". The Birmingham Post described it as "quite possibly the worst film ever made", while the Independent on Sunday stated that the film was "a strong contender for the title of worst film of all time". Donald Clarke of The Irish Times stated that "Sex Lives of the Potato Men attracted some of the worst reviews in living memory". The film magazine Empire placed it at no. 7 in its list of "The 50 Worst Movies Ever". The film has a 0% rating on Rotten Tomatoes out of 14 reviews.
