GREATEST HITS albums are pure gravy for the record companies. They take music they've already paid to record, reassemble it in new combinations and reap the profits with almost no investment. So at the end of every year, you see a rush of "Best of..."' albums hit the stores.

It isn't so easy for the record buyer. Some anthology albums provide a service by collecting the cream of an artist's career and leaving out the filler. Some artists, however, haven't produced enough cream to fill up two sides of an album, while others have produced too much cream for any reasonable sampling.

The real dilemma comes for record buyers devoted to a particular artist, who may already own all the artist's previous records. To induce such devotees to buy a greatest hits album, the record company will add one or two previously unreleased songs, thus leaving the true fan to decide if those two songs are worth seven bucks.

Among the artists best suited for greatest hits albums are those who gear themselves to the singles market. They concentrate on a few songs as possible hits and let the others take care of themselves. A good example of this practice is the Steve Miller Band whose pleasant pop fantasies surrounded by technological special effects are good, if insubstantial fun.

Miller's albums usually contain a few nuggets and lots of sand. But his Greatest Hits 1974-1978 (Capitol S00-11872) collects the brightest pieces in the pile: "Take the Money and Run," "Dance, Dance, Dance" and "Jet Airliner."

Another good group for an anthology is the Marshall Tucker Band. They have distinguished their brand of Southern boogie from the tradition of the Allman Brothers and Lynyrd Skynyrd by adding a genuine country twang and fresh reed playing. The group, however, has fallen into a formula, repeating the same mixture of country, blues and rock n' roll over and over again. Greatest Hits (Capricorn CPN 0124) collects their best variations on that same theme.

The best candidates for the "Best of" albums have always been Motown artists who often make great dance singles but fluffy albums. This is as true of the new Motown superstars -- The Commodores -- as it was of earlier artists like the Supremes and Four Tops. The Commodores' Greatest Hits (Motown M7-912R1) collects those singles -- including "Brick Hose," "Easy" and "Three Times a Lady" -- in one convenient package.

Earth, Wind & Fire, by contrast, has two sides to its personality. They make driving dance singles for the radio, but their albums complement the singles with more ambitious jazz arrangements. The Best of Earth, Wind & Fire Vol. 1 (ARC/Columbia FC 35647) only represents the singles side of the group and omits much of the band's most imaginative music.

Sometimes a greatest hits album collects odds and ends recorded by an artist never included in a major album. Wings Greatest (Capitol S00-11905) IS A GOOD, EXAPMLE. It collects three singles that had never been on album: the Penny Laneish "Another Day," the bagpipe-swelled "Mull of Kintyre" and "Junior's Farm," Paul McCartney's best rocker since "Get Back." It also rescues the infectious "Hi, Hi, Hi" from an otherwise awful album and the original production-thickened "Live and Let Die" from the otherwise useless soundtrack.

It would be hard to collect all of Paul McCartney's best solo music on one album, but almost all of what's missed on Wings Greatest can be found on Band on the Run (Capitol) and Wings over America (Capitol). Together the three albums make a convincing case that McCartney is the only ex-Beatle to maintain his talent since the breakup.

Some artists, however, have simply produced too much good music on each album to come up with any satisfying sample package. Anthology (Capitol SB-KO-11856) collects 20 of the Band's best songs, all of which are inarguably good. But when you start to consider that songs like "When You Awake," "Tocking Chair," and "The Rumour," were left off, you begin to see the futility of such a project.

The same is true of Steely Dan/Greatest Hits (ABC AK-1107/2). Here the song selection is even less defensible, overlooking some of their best known numbers: "FM," "Deacon Blues," "Aja" and "The Royal Scam." Both the Band and Steely Dan are major rock 'n' roll groups that should be collected album by album.

Some greatest hits albums are limited by the territorial imperative of the record labels. "FM" was kept off ABC Records' Steely Dan/Greatest Hits because it was recorded for an MCA soundtrack. The Very Best of Dave Mason (ANC BA-6032) only includes Mason's early work as part of Traffic and as a solo artist with Blue Thumb and ABC. While it includes the two highpoints of his career -- "Only You Know and I Know" and "Shouldn't Have Took More Than You Gave," both from Alone Together (Blue Thumb) -- it doesn't include any of his recent work for Columbia such as the hit "We Just Disagree."

Similarly, The Best of Joe Walsh (ABC AA-1083) includes two songs the guitarist recorded as leader of the Hames Gang and eight others from his solo ABC albums, but none of his work the Eagles or from his newest solo album, But Seriously Folks (Asylum) which included the hit, "Life's Been Good to Me."

The Isley Brothers' Timeless (T-Neck KZ2-35650) is a two-record anthology but only culls songs from the second half of this group's 20-year career. Their early R&B hits, such as "Twist and Shout," which so inspired the Beatles are far better than their more recent monotonous funk collected here.

It's difficult to understand the logic behind Profile/The Best of Emmy Lou Harris (Warner Brothers BSK 3258). Harris has only had four previous albums and no big singles to speak of. Many of the songs on Profile are quite nice, especially Chuck Berry's "C'est La Vie," Dolly Parton's "To Daddy's the Louvin Brothers' "If I Could Only Win Your Love" and Harris' own "Boulder to Birmingham." But many of the songs omitted are just as nice: Rodney Crowell's "Leaving Louisiana in the Broad Daylight," and Parton's "Coat of Many Colors," to name a few.It's just too early in her career to justify a retrospective.

There are several disco greatest hits collections surfacing, such as The Best of the Trammps (Atlantic) and The Best of the Sylvers (Capitol ST-11868), but what's the point? Most of these groups find one hit formula and repeat it endlessly. The best disco compilation is still Saturday Night Fever (RSO) which includes the Trammps' "Disco Inferno."

Some albums of "greatest hits" don't have enough oomph to even make it as a record by themselves. Barbara Streisand's Greatest Hits Vol. II (Columbia EC 35679) collects her new duet with Neil Diamond, "You Don't Bring Me Flowers" and equally sappy songs from her sentimental movies: "A Star Is Born" and "The Way We Were." What a waste of a good voice.

Barry Manilow's material is every bit as sappy as streisand's and Manilow has even less of a voice. Barry Manilow's Greatest Hits (Arista AZL 8601) contains two records worth of the schmaltziest music of the day. Manilow is one of those people who will sell millions of records without leaving a single influence on American music.