Preston was in charge of Scottish side Livingston when Snodgrass was a rising star.
He told the Pink 'Un: "He was very highly thought of at Livingston.
"He was the jewel in the crown, but the problem was the off-the-field stuff.
"You'd say to him he had to behave as a professional, but he was 17, a young boy with a fair amount of money and as young boys are wont to do, he wanted to get out, have a laugh, party, drink...
"He would miss training, but once you got him out there he was brilliant, fantastic, a youngster with great ability who loved playing football.
"His right foot isn't bad at all, but his left foot is God-given. You don't like to see that ability go to waste, but I was worried and when John Robertson, as manager, put him out on loan to Stirling Albion, I did wonder, 'is that it?'.
"But he came back, screwed the nut and has realised that gift."