Although - in general - the staff are pretty sh!te and don't know the first thing about what they're selling, it's actually a pretty handy shop to have nearby. I'm into cars and mountain bikes, so being able to nip in and buy something I need there and then really isn't a bad thing. I would never ask the staff for any kind of advice though, and most certainly wouldn't let them anywhere near my car or bike! As others have said, it's useful for consumables and branded products where you know what you're buying - may not be the cheapest place to get them, but if you need something on the spot and know what you're looking for it's fine.
The level of care and attention you're likely to receive from the staff has been made pretty clear to me, when on a couple of different occasions at my local store I've been told: "The alarm might go off when you walk out because this thing has a security tag in it that I can't remove. Don't worry though, nobody will come running after you." I literally told the bloke that I'd just fill my pockets next time, then... (I wouldn't actually, just in case anybody starts hating on me.)
