Just another thing I don't think has been covered. If the dog in question that's on trial would usually only do an hour and then jack !!! What's to say the man selling it on trial hasnt deliberately laid it up for months and is fresh as a daisy !!! You dig it once or twice, think it's ding dong then part your money only to be well caught !!! 90% of the time any decent dog goes to friends or digging partners, not halfway round the country to Joe bloggs that is looking a terrier!!!