On the whole, the tarantula didn't look very happy about being in the bathtub. I imagine it had better things to do: snacking on a cockroach, perhaps, or just waving its big hairy arms around and scaring the bejesus out of everybody. Instead it had somehow managed to penetrate the defences of a $500-a-night hotel room in southern Mexico, and was now lost in a white fibreglass universe, with only a bar of exfoliating soap for company.

Fortunately, I wasn't in the room at the time: I was browsing through TripAdvisor.com, looking for reviews and photographs of the Fairmont Mayakoba resort near Playa del Carmen where I had booked a holiday on the recommendation of a travel agent. It had seemed old-fashioned, using a travel agent. And now I had gone and ruined it by searching the internet for post-purchase validation, only to find a review (photographs included) from a guest who had ended up with a spider the size of a cocker spaniel in his room.

These aren't easy times for holidaymakers, that's for sure. With jet fuel now more expensive than liquid plutonium and skin cancer practically a certainty unless you encase your entire body in concrete, more is at stake than ever. And yet there is so much information available on destinations, you need to book a holiday just to do the research necessary to book a holiday.

Travel agents are no substitute for your own research. And after the publication of Do Travel Writers Go To Hell? (there was no need for the word “do” in the title, never mind the question mark), we know that travel guides are written by people whose idea of an “in-country” assignment is sleeping with a Colombian air hostess.

Which leaves us with TripAdvisor - a website whose influence is surely right up there with God and Wikipedia. But should we trust 15 million reviews written almost exclusively by people with margarita hangovers and sunburn? Another problem: not everyone has the same tastes. For example, people with more money than you will almost certainly conclude that your favourite little place on the beach is a festering dump with inattentive service - while someone used to ten-quid package holidays on the Costa del Booze might conclude that it's overpriced and snooty.

Which brings me back to the tarantula. I spent the first few hours at the Fairmont checking behind the loo and above the shower for an eight-legged interloper. Nothing.

The relief lasted all of one night, until I awoke to a smell so toxic it made my eyes water. “Burning garbage, Señor,” explained a bell boy, pointing to the horizon beyond the resort, above which a black cloud loomed. Fortunately, by late afternoon, the smell had gone. But it was back again the next day. Somehow, TripAdvisor had made me fear the one thing almost guaranteed never to happen while overlooking that the entire “eco-resort” is located within smelling distance of some kind of garbage incinerator.

Next time, I think I'll just stick a pin in a map and take my chances.

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