I tend to think of it as "is the magazine content worth the purchase price" the actual advert ratio doesn't really factor in. A local camera magazine (I'm in Australia BTW) has some interesting articles in it, but the rest is adverts or worse still, adverts disguised as reviews (same layout and look as real reviews except for some fine print saying it's really an advert). I'll browse the interesting article at the newsagents (newstand,etc) but won't buy it for the one article. On the other hand, I buy several UK based magazines that are 2 or more times the price of a local one, but believe them to be better value for money since all aspects (except the adverts for stuff I can't really buy although these can be interesting to see what's available anyway! are interesting and I read them cover-to-cover.