Four degrees of Suckeration. 
You know, the verb "to suck" has taken over the world. When I used to say, 15 years ago, "I suck at Asteroids", women actually got offended. Now everyone says it on family shows and "Meet the Press". The one thing they haven't adopted from our old 1960's New York slang is the traditional "this" response. Example. The priest says "Dominus vobiscum", and you say "Dominus THIS, Padre", and grab your crotch. This works on all occasions and as a response to any comment. (Or, as an alternative, you can grab your crotch and say "I'll give you your Dominus right here, Padre", but my friends found this variant too verbose.). To relate this to the "suck" verb, one guy would say "your cigar sucks", and the other guy would grab his crotch and say "suck THIS", and there you have plenty of merriment and an instant Algonquin Round Table of witty repartee for all occasions.
Now my point here is that the co-opting of "suck" by the mainstream culture leads to a lack of gradations. Is it fair to say that Cher's singing sucks, when this is the same way you would describe Yoko Ono? Of course not. So I therefore propose four degrees of suckeration. To stay on the musician theme for a minute, here's how it would work. 
First degree of suckeration. People who are OK, but not really as good as you might expect from the success they've achieved. An example would be Jewel. If you got all your cousins together, Jewel would sing about as well as the best one. She has a pleasant voice, can carry a tune, knows some guitar chords, looks good. She's OK, you just can't quite figure out why she's a star and 100 million other equally talented women are not. 
Second degree of suckeration, people who really aren't good enough to be doing this professionally at all. If you assembled your cousins together and had a karaoke contest, they would finish in the middle of the pack. Cher and Jerry Vale would be in this category. 
Third degree of suckeration, people who don't have a clue how to do what they are supposed to be professionals at. Your most incompetent cousin could do it as well. Sid Vicious belongs in this group. 
Fourth degree of suckeration, people who are so bad that they not only can't do what they are supposed to be good at, but they cause nausea and/or laughter when they try to do it. If these people were your cousins, you wouldn't even admit it. And if you had a family karaoke contest, you'd have a kindly aunt distract them to another room to look at baby pictures. Examples would include Carol Channing, Yoko Ono, and Shatner.