Chainzsaw :
Uhh I use a plastic/rubber hose. So there is no issue with static. Also - i've used it many many times - and NEVER EVER HAD A PROBLEM USING A VACUUM.
Who told you to never use a vacuum? Whoever it was, is wrong. So don't comment with ridiculous out of this world thoughts.
You just have to be careful when using the vacuum not to damage components (also, you have to make sure you disconnect your computer).
You are grossly misinformed and I really suggest you read up on the subject matter.
Plastic hoses? You realize carpet is also made of essentially plastic right? yet it is one of the largest sources of ESD in a home. Something doesn't have to be metal in order to create ESD, in fact many of the biggest sources are not made of metal. It would actually be better to use a metal hose that is grounded than a plastic one.
You could probably somewhat safely vacuum the fans and or filters of a PC case fairly safely if you were extremely cautious but I would not recommend putting a vacuum anywhere near the inside of a PC case. I saw a video on youtube a few years back that was taken in a pitch black room of what is happening when you use a vacuum and it looked like a mini elecrical storm all over the area near the end of the hose.
You have either been EXTREMELY lucky, and possibly live in a very humid environment which will help a little, or you haven't kept a PC long enough for it to degrade.