Straight arrows DO make a difference. I shot target archery for 20 years (2 time Wisconsin state champ and 17th in the nation at the nationals). I'm not sure you can straighten the new carbon/alum arrows but MY guideline was they had to be .0005 or less or they would not group well. These are target arrows. Stick a broadhead on the end and the straightness (good or bad) will determine how much that arrow can plane off during the shot.

Easy way to tell is (for a right hander) open your left hand wide, palm up. Put the point of the arrow tip in the middle of the palm. On your right hand put your thumb against the first finger, fingernail up and rest the top of the arrow (below the fletching) on the "v" formed. Now blow on the fletching. If the arrow vibrates or jumps it's not going to shoot well. After awhile of doing this you'll become an expert at telling good arrows from bad. If you have an arrow straightener or v-blocks check the point of your broadhead. You'll find frequently this is where the problem (if any) lies. Hope this helps.