Ask Papa Johns, who spend years defending "Better ingredients. Better Pizza." They were found to be in violation because (as wiki nicely sums it up) "At trial, the court agreed with Pizza Hut's argument that Papa John's slogan did not constitute statements of literal fact – that "fresher ingredients" do not necessarily account for a "better" pizza."
The ruling said:
The slogan, when utilized in connection with some of the post-May 1997 comparative advertising – specifically, the sauce, dough and stuff campaigns – conveyed objectionable and misleading facts.
On appeal Papa Johns prevailed, but the findings were not overturned, only the damages since: "Pizza Hut has failed to produce any evidence demonstrating that the facts conveyed by the slogan were material to the purchasing decisions of the consumers to which the slogan was directed."
I think I can make a really good case that if I search for "Archery Tag" and your ad pops up and says "Foam Tipped Arrows - Used for Archery Tag & LARP" and I buy your off brand thinking it's an approved product instead of my official branded one - then then your ad was very material to my purchasing decision. The phrase "Foam Arrows - Better than Archery Tag Safety Tested with 4 year warranty" also implies to many reasonable people that Archery Tag branded ones are not safety tested..which is obviously going to require some burden of proof.
The ads still showed up last night if you search for "Foam Arrows" and "Archery Tag arrows". http://imgur.com/a/6Xu7x but I don't see them today. Pulled as of this morning perhaps?
The puffery exemption only goes so far, and hijacking a brand name to drive traffic to your store - while still being tested in courts of law around the word since internet law is a burgeoning field and few judges understand Google adsense - is pretty much the opposite of simple exaggeration. Puffery only protects against things that can't be taken seriously. The rule is that "Best" can be used without having to backup your statement. When you use "better," you need to have proof to substantiate your claim. Pizza Hut meanwhile had proof that better ingredients don't actually make people prefer Papa John's. It's a statement of fact that the LARPing.org arrows are approved through an association with the trademarked brand name "Archery Tag" and are not just generic LARPing arrows - and that they are higher quality and better. If the ad was either of the following it would pass muster:
"Foam arrows for LARP"
"The best foam arrows for playing arrow tag"
For comparison of how limited the puffery exemption is, in Jay Norris, 91 F.T.C. 751, 847 n.20 (1978) they found that they "must conclude that the use of "electronic miracle" in the context of respondent's grossly exaggerated claims would lead consumers to give added credence to the overall suggestion that this device is superior to other types of antennae". You can't even imply that your product is better as a "miracle", unless it really is superior.