Yeah - I do worry about making a request that might "verify" some other legitament user's url, so I won't do this if the identifiers looks like consecutive numb

Yeah - I do worry about making a request that might "verify" some other legitament user's url, so I won't do this if the identifiers looks like consecutive numbers, but if they look like guids I'm perfectly happy to blast 10,000 or 100,000 random ones back at them.