Do I have to pay for unsuccessful requests?

If the request was unclear or incorrectly worded, tokens will not be spent. Debiting occurs only in cases where the request is made correctly and a response is received from our service. 

However, if the request was not clear on the part of the model manufacturer, then in this case the problem is not on the side of our service, and the tokens will be debited according to the standard debit rules.

You can calculate the cost of requests for the models you are interested in here.