I ask my users to provide a Paypal account on which they will receive automatic payments (through Paypal PHP SDK) and I want to be sure such account is valid ( active and ready to accept payments) before the first payment occurs (e.g. when they sign-up. Of course I'm aware the account status may change in the meanwhile). Does Paypal provide a better way (or is there a smarter flow) to achieve this without a classic 0.01$ transaction?
You can use one of our classic API called GetVerifiedStatus.
This API basically check against the status of PayPal Account, whether it is Verified or Unverified. You can even get whether the account is a Business account or Personal Account. There are a lot of other information which you could get.
Do visit the specific API's page for more information on the response values you would get upon calling this API.