Imagine using a site that says it will give you soft leads on quotes for people who you only have a first name and last name initial. You have no phone number email address no concrete proof that the quotes are from real people and not computer generated.
What is for certain is that you will be charged for a bulk of credits. Sometimes the quote will cost 2 credits other times 11 credits. You will find yourself spending up your credits on no time with "zero" results.
Now you're probably thinking, what if someone is getting the gig? Well I am a DJ who has a big name in radio. Whoever I apply for gigs outside of thumbstack I have a 75% success rate. Not to mention I've even lowered my fee on thumbstack below industry standard and still no response.
Did I mention my work region is withing a very small area, which makes this even more suspect.
In conclusion, you should just find another means to find work. Thumbstack is a rip off