Those shocks usually start with selection, firstly for the tour itself and then for the Test series.
In 2009, the inclusion of Wales wing Leigh Halfpenny and Ireland flanker Alan Quinlan were major talking points, as were the original exclusions of national captains Steve Borthwick, Mike Blair and Ryan Jones.
In 2005 it was the injury-prone Jonny Wilkinson who received most of the media attention, while in 1997 the decision to select a host of former rugby league stars such as John Bentley, Scott Gibbs, Alan Bateman, Scott Quinnell and Alan Tait, as well as uncapped Leicester centre Will Greenwood, received plenty of column inches.
In 2001, Graham Henry's appointment as the first foreign coach of the Lions was met with a mixed reaction, as were the inclusions of the untried Jason Robinson and Simon Taylor.
And while many of Henry's selection of his own Wales players were nailed on certainties for the tour regardless of the coach, there were a number of critics who were quick to suggest that a handful of Welshmen wouldn't have made the trip Down Under had the Wales boss not been in charge.
Llanelli utility back Dafydd James would have been among that list, yet the powerful wing cum centre proved to one of the biggest success stories of the tour.
James proved that the Lions environment can be the making of previously unsung players - those who have sometimes ducked beneath the global radar but who prove they can perform under the brightest of spotlights and on the biggest stage of all.
Dafydd James was Mr Consistent for the 2001 Lions
The then 25-year-old arrived in Australia as a solid performer with plenty to be proud of but he left for home as a record breaker who had joined an elite list of his countrymen while representing Britain and Ireland's elite.
James followed Lions legends Gerald Davies, JJ Williams and Ieuan Evans as the fourth Welshman of the modern era to play on the wing in every Test of a Lions series.
Williams achieved the mark in 1971, Davies in 1974, Evans 1989 and 1993 but very few observers would have predicted that James would match them in the first tour of the 21st century.
"I don't think anyone could say that I was in most people's Test XVs before the tour started and there were probably some who wouldn't have even selected me in their squads," James told Rugby World shortly after his one and only Lions tour.
"It's a huge honour coming on a Lions tour and with the number of great players in the squad I can only be delighted with what I achieved. To play for the Lions is a dream but then to play in all three Tests is magnificent."
The Lions brought out the best in James
James did more than simply play in all three Tests against the Wallabies nine years ago - he got on the scoresheet too as the Lions recorded a crushing 29-13 win in the first rubber.
For James, proving himself among the very best the world has to offer wasn't something he took lightly.
He may not have been the first name on most people's lips when it came to selection but the Lions had been a major goal throughout his rugby-playing career.
"I was on standby for the Lions in 1997 and then I said to myself, 'I want to be there in 2001'," added James.
"Almost touching it in 1997 and then having to sit and watch it on the TV gave me an added incentive to make sure I wasn't in the same place four years after.
"I set myself goals throughout the year, with the big target being the Lions.
"And if that meant training harder and not going out as much as I had done before, then they were small sacrifices to make. I used my time last summer to my advantage, working on different aspects of my game.
"My goal was to get in the Lions squad and once I got there I was determined to go a step further."
James played in all three Tests against Australia
When he did finally get the Lions call, the experience didn't disappoint.
James saw first-hand how passionate the Lions supporters really are; got to work alongside people he had only ever seen as opponents rather than team-mates; and had the honour of being handed his first Lions Test jersey by the great Willie Jon McBride.
The tourists may have suffered Test heartbreak against the World Champions but the opportunity to be a part of the Lions culture will live with James forever.
"The buzz and atmosphere of a Lions tour is better than anything I have ever experienced, there's no doubt about that.
"There were so many Lions fans on the trip - and many of them Welsh - that when they started singing it felt like we were at home.
"There was one moment in Melbourne before the second Test when we left our hotel and there were what seemed like thousands of people in the lobby and the hairs on the back of my neck stood up. It was an incredible feeling to know that you were backed by all these people who had come out to Australia to support you.
"I also enjoyed the challenge of working with other professionals from the other Home Nations, including coaches I hadn't worked with before like Phil Larder. It was totally different from anything I have experienced before.
"I was a bag of nerves for the first Test meeting. I'm always nervous before a game but this was so special I was shaking when Willie John came in. He started talking and it was one of those moments you want to just go on and on.
"He wasn't like I thought he would be - shouting - he was quiet and talked with feeling. But you knew the man meant business. A lot of people will never experience that sort of thing. I know I'm lucky."