Is there anything concerning about buying a half-price "test helmet" from my local bike shop? I just bought a Lazer O2 helmet and am loving it, but I got it half price from my local bike shop because it's a "test helmet". This means that people who want to test ride their bikes use these helmets, but the person I talked to mentioned that this helmet was not used very often. It is white and has the words "test test test..." printed over a top portion of the helmet- it does not look like a sticker. I am wondering if anyone has had experience with these types of test helmets and if there is anything I need to be concerned about. It doesn't seem like the helmet is any different from the regular O2 helmet, other than the print on the top.

Thank you!
A recent study investigated the impact performance of 675 used helmets (some as old as 26 years) without signs of damage.  (They collected 1500, and eliminated helmets with signs of damage). They all passed, except four. Three that failed were only made to meet the  old ANSI standard, and the only newer helmet to fail was a recalled model.

Because all of the helmets were used, some of the 675 would have been incurred some slight damage (e.g., being dropped, or bumped through regular usage) without showing direct signs of damage .  The fact only 4 failed, and those 4 had other issues, this suggests if you don't see visible signs of damage on a modern helmet, it is probably okay. In fact given the large sample size and consistent ability to pass the impact testing, I now have a lot more confidence in the quality of modern helmets than I did before.  

For your helmet, makes sure to carefully inspect it.  If you don't see visible signs of damage you are probably fine,  assuming that the helmet was properly manufactured (i.e., NOT a grey market helmet), that it has passed all the modern certifications (i.e., check for the certification stickers), and that it was not a recalled model.