Compared to iPods LPs are a lot of work. First you have to put the record on a turntable platter, cue the tonearm over the lead-in groove, and then gently lower the "needle" into said groove. When the record's over, you have to raise the arm and return it to the rest. If that sounds like hard labor stick with your iPod. But to audiophiles the turntable/record playing ritual is part of the analog experience, a preamble of good sounds to come.
Thing is--the stylus tracing the microscopic world of groove wiggles encounters more than just wiggles--whatever dirt and assorted crud that's adhered to the vinyl adds its own noise, clicks and pops to the music. Sure, when things are really bad you could gently wash the LPs with baby shampoo, rinse with lots of water and dry. That might help, but the deep down grime at the bottom of the groove will still be there, and still audible. The ground-in crud can dramatically increase what we perceive as "record surface noise." Record brushes can sweep some of the surface dirt off, but at the end of the day the only way to get the deep down stuff is to use special record cleaning fluid and suck it off with a vacuum. that's exactly the way record cleaning machines work--they squeeze more analog juice from used and even new records.
Nitty Gritty, based in California, has been making vinyl vacuum machines since 1981. Marc Phillips' review of the Nitty Gritty Model 1.5 in Tone magazine is available as a PDF here. Phillips provides an in-depth examination of the ins and outs how these machines work. To offset the price of the machine groups of vinyl-philes sometimes chip in and buy a Nitty Gritty together and take turns using it. And yes, I've used Nitty Gritty machines and can testify to their effectiveness.
After you've checked out the Nitty Gritty review, look over the rest of Tone. It's a beautifully laid out 'zine, chock full of cool audiophilia.