Now the Northern Irishman is attempting to help Aberdeen finally make their mark - starting with a clash against Neil Lennon's side today.
McGinn featured only fleetingly for the Hoops after his move from Derry City in January 2009 but he has flourished in Scotland's top flight after returning north of the Border from a loan spell at Brentford and joining the Dons.
Despite the Pittodrie side again struggling last season, the forward was a stand-out performer and his form will be crucial as they set their sights on a far loftier league placing under new boss Derek McInnes.
The 26-year-old played his part in a memorable evening for Northern Ireland in midweek as they beat Russia in a World Cup qualifying clash and while he may not have starred on the big Parkhead stage, he still has the ability to shine.
"He came here when he was really young," Samaras said.
"He is a good player, he has really good pace. He played some really good games here for us and scored some goals.
"It is really difficult to play for this club with the pressure and the competition from players. You need to be strong mentally and physically to get through everything. He left to go down south and when he went to Aberdeen he realised his talent.
"From day one when he came here we knew he was a good player but sometimes it is difficult to play and take your chance at a big club like here.
"I never played an official game against a former club. If you are asking about Mo [Bangura], I think he had something to prove. For other players, it depends how you leave a club.
"If you leave and think 'my circle is finished, I need to walk away and find another club' I don't think you have something to prove.
"If you don't have the right chances and you don't play a lot and don't go away with the best things then you need to come back and prove something."
The lunchtime meeting between the Dons and Lennon's side presents each team with their first real domestic test of the campaign.
While the champions only have a victory over Ross County to their credit so far, their hosts this afternoon have lived up to the pre-season predictions, taking maximum points from meetings with Kilmarnock and Motherwell in the opening fortnight.
Celtic are expected to cruise to the SPFL Premiership crown in the coming months and while Samaras is open-minded about who will end up best of the rest, he is keen to see McInnes breathe fresh life into the under-achieving Dons.
He said: "It will be a long, long season. I really don't know how the season will be. I will need to see all the teams. After 10, 12 games you can see what teams will be in the first three or four positions
"It is a great club with a great history from the 1980s. They were a really good Scottish club in the past and we need them to be reborn to help Scottish football.
"Hopefully they go on for the next years and not one year. They need to build from this year to the next year to again become a top team in Scotland like they used to be."
In any other week of the season, the trip to Pittodrie would be an eagerly anticipated clash but events in midweek and fixtures to come mean the Dons meeting has lost some of its lure for Celtic.
Lennon has welcomed back Scotland trio Scott Brown, James Forrest and Charlie Mulgrew from their Wembley near-miss and will take his side to Kazakhstan straight from Aberdeen as they gear up for their Champions League showdown with Shakhter Karagandy.
Brown turned in an eye-catching performance against the Auld Enemy on Wednesday night as he mixed it with a host of Premiership stars, but Samaras has no fears about his skipper being lured away from Parkhead to test himself on a more regular basis.
He said: "His quality is at a really high level. He is the captain of Celtic, he has been here for seven years I think, six months longer than me. He is one of the captains of Scotland.
"Sometimes you don't need to go somewhere to prove something else or for people to believe in you. If people believe you are not good enough, you don't need to change all this to go and prove that you are good.
"His mentality is that he will never quit Celtic to go to a club in the Premiership and fight just to prove something.
"He will stay here and play European football and win titles. If he does not want to leave, his door for other teams will close. Nothing will be in the media.
"For sure, there are clubs interested in him. But it is a 'no' straight away and that means the door is closed, there is nothing in the media, no rumours, nothing.
"I am sure there are offers for him."