Adulterators use very clever methods and the users do not have adequate knowledge of original spices. Hence it has come to be difficult to detect adulteration easily. It is all the more difficult in the case of ground spices and masala.
However we can still use some quick and handy methods which may indicate adulteration.
1. You find that for the same effect of taste and smell, you have to use more quantity now.
2. The one item you now get is given at much discount , even though the unground spice ingredients are still selling at high cost.
3. Add water to a little of the spice and stir and allow to settle. If you find some thing unusual floating or settled at bottom and different from the spice, then you can doubt adulteration.
4. In 3 above if after washing, the spice powder loses its colour, then you can doubt adulteration.
5. If you feel the texture and feel light and different, or extra heavy, then you may doubt adulteration.
One way you can avoid adulterated goods is to stick with the local vendor, who is in the business for decades and has a reputation locally and knows you personally. A chat with him can help you how to detect adulteration and which type and brands to avoid.