The Report button will get a polite reply from eBay, but a single Report from a single member is not evidence. Multiple Reports from multiple members would be different.
If you have been in a transaction, opening a Not As Described dispute and getting a refund is much more effective.
Unless the seller cooperates and refunds promptly, he gets a Defect and those lead to higher fees, restrictions on the number and /or value of listings, and possible closed account.
A dumb criminal will attempt to schmooze the buyer into not Disputing, or into waiting until the deadline for filing a Dispute passes. This is dumb because it does not always work and the buyer has backup ways to Dispute.
A smart criminal will refund promptly and not fight a Dispute, because by doing so there are no Defects, no raised fees, no restricted listings and the sketchey seller goes on selling.