In a recent Consumer NZ survey, Kiwis estimated one "big purchase" in every seven was a bad buy. That's not to say one in seven was faulty – although some no doubt were – but many just didn't perform as well as expected.

It's often said "you get what you pay for", and it would be great if price was a reliable indicator of performance. But when there's a $25 slow cooker currently available that cooks better than models 10 times the price, and a $50 carry-on sized wheeled suitcase that stands up to abuse as well as a $600 premium-branded model, it isn't always true.

Our objective testing is different from many product reviews found on the internet and recommendations from friends and family, who might only consider the performance of one or two models, and supply their recommendation tainted by their own expectations and needs. It's why our reviews are trusted, and often the only truly independent product performance tests available.

Sitting at the top of our dishwasher test is an $800 model with better washing, drying performance than many "premium" branded models. At the bottom of that list is a model from one of those "premium" brands – which is "just OK" at washing and poor at drying. While everyone should avoid the worst performer, it doesn't mean the top-scoring $800 model is the best choice for you.

To avoid those "bad buys", you need to consider more than pure performance, there is no one "best" model for everyone. While the main reason for a dishwasher is washing and drying your dishes, you might need other functions like a delay timer, or shelves that adjust to suit your particular pots and pans if the dishwasher is to really work for you.

By using our independent test results, you can narrow your choices to a smaller range of models that perform well, then look for functions that suit you the best. That's where other subjective reviews and opinions become useful – whether from other Consumer NZ members, internet reviews or friends and family.