ahh bless quality score
I love how it works.. example below... ok it's not credit cards and it's not monkeys but figures are real :
site is monkey credit card orientated
"monkey credit card" is now £5.00 a click even though ctr is 9.83% and conversion is 23%
yet
"monkey credit card co uk" is 0.10p a click even though ctr is 2.1% and conversion is 3.55%
bearing in mind "co uk" isn't on the page anwhere domain is a .com
so the most relevant and best converting of the two is spanked for poor relevancy yet it's more relevant than the second which converts FAR poorer, yet is only 10p a click, the first one was around 45p a click before the Quality

score spanked it.
or hows this baby for relevancy :
"monkey cards" ctr is 25% and conversion is 66.67% was 8p a click !!!! now £5.00
now just how is that "irrelevant" which is what the quality score would be inferring by saying £5.00 please .... gah
gotta love that quality score.. reckon it's named that as the guys at G sat down and said how can we increase revenue.. some nuclear fusion expert said oooo I know.. let's charge more for popular keywords and thinly disguise it as relevancy score .. someone must have just said "OMG that's QUALITY !!".. let's call it the "Quality Score" ... then they all fell down laughing.. grabbed another handfull of columbian marching powder from the fruit bowl and partied the night away on their diamond studded segways
but seriously the answer is content, and substance.. build something that's worthy of being a site in it's own right, something more than bounce in and out pages.. it's a pain but if you want to play on G you have to dance to their tune so it's best to over engineer it and go for it big stylie, at least is should (fingers crossed) be future proof for a good while then