But in the case of the Vauxhall Signum I have to hold my hands up and admit I was wrong.
When I first drove the car I really didn't like it at all. The general shape looked to me like a Renault Vel Satis that had gone wrong, the dashboard reminded me of something I saw in a Mercedes-Benz truck a few months ago and as for the fact that such a big car can only seat four adults, well...
But that was then and this is now. In the past three weeks our long-term Signum has accompanied me on several journeys the length and breadth of Britain and now I am beginning to see just how good a high mileage companion it really is.
I'm getting used to the shape and where once I saw ugliness I now see grace. I'm getting used to the dash too – where I once saw old lorry I now see solidity with style. There are several things I just love about this car. For starters, the driver's seat is a dream. It moulds itself nicely to the body, with plenty of side support yet a nice soft feel.
And on long motorway trips the Signum proves that big cars don't have to behave like boats. It boasts surprisingly good road-holding for such an enormous vehicle and with 155bhp available from its nifty 2.2-litre direct injection petrol engine, there is no shortage of pulling power.
Personally if I was taking the Signum on a three-year lease, I would like to have an automatic gearbox – it somehow seems to suit the car better than a manual. But that's a £1,300 option which bumps up the carbon dioxide rating to 211grams per kilometre.
The net result is that a 40% taxpayer's benefit-in-kind tax bill would rise from £138 to £189 per month – ouch.
But amid all this euphoria, there is one thing about this car that is driving not only me but all my colleagues to distraction – the dreaded indicator stalk. Let me explain: For round about 50 years now, indicator stalks have been going about their business quietly with an unassuming air. As they work so well, no-one has ever bothered trying to improve them – until now.
In a bid to re-invent something that didn't need re-inventing Vauxhall, far from improving this item, has made it worse. Far, far worse.
The theory is that if you nudge it lightly, it ticks three times and cancels itself and if you push it harder it stays on until the turning steering wheel column cancels it again. In practice is just doesn't work. Sometimes when you want it to stay on it goes off and sometimes when you want it to go off it stays on. And occasionally, if you try and cancel it yourself, it goes from left to right or vice-versa. And that's dangerous.
I would like to meet the man or woman who is responsible for designing this ridiculous piece of kit. I would listen while he or she explained the 'logic' behind it and then take them for a drive to prove how annoying it is.
So here's a united plea to Vauxhall from all the road testers at Fleet News. PLEASE dump this annoying gadget in the bin where it belongs and go back to the old system.
Company car tax bill 2004/05 (40% tax-payer): £138 per month