What makes them kick hairs is stress. The first means of defense with most American tarantula species is kicking hairs, before turning to biting. A lot of Brachypelma species will kick hairs at you at the drop of a hat, and the B. boehmei is probably th worst when it comes to that. They're gorgeous and they're a good species to start with because they're not very venomous and don't require difficult circumstances, you're just bound to get hairs kicked at you.
It varies from animal to animal how the temperament is. They can even change attitude between molts.
You can avoid it by not buying an American tarantula species
But if you want a tarantula, you want one of those. African or Asian spiders are more difficult to keep, most of the times extremely fast and venomous.
You can minimize the hair flicking by disturbing it as little as possible. Handling for example is extremely stressful for a tarantula and so it's best to not handle them.
The Grammostola aureostriata does have the hairs but I've never had one that was easily stressed out and never had one flicking the hairs at me. I've had quite a few of them. If someone asks me what the best species to start with is, I tell them aureostriata.