Sonko has revealed his frustrations at rules that have forced him to watch on from the stands but still take home his wages.
The Senegal international joined Portsmouth on loan last campaign, but tallied just 17 Championship starts for the South Coast club.
Sonko was restricted from representing Pompey as rules state a team can only have five loan players in the squad on a match day.
He told The Sun: "This has been a dreadful experience. I've taken the money because that's what is in the contract. But all I've wanted to do is go out and earn it.
"I've been caught in an infuriating web of rules and red tape which some managers are not even sure about.
"At Portsmouth I had to sit in the stands and watch my team lose because the rules mean I could not even be in the squad.
"The fans are sitting around me and God knows what they think? I'm sure that if many clubs don't even know the rules, then they don't.
"So to them I must have looked like some lazy footballer - picking up almost ?20,000 a week but could not be bothered to play.
"The last three years have been a mess and it needs to be sorted. Far from being lazy I feel like I've been restricted from doing my work.
"What other business would have such complex rules that stop people moving around and getting the best out of themselves?"
Sonko joined Stoke from Reading in 2008 and has since had a loan spell at Hull City, where he made just nine league starts, as well as at Portsmouth.
Of his time at Fratton Park, Sonko reflected: "I was one of seven players on loan because the club was struggling to sign players permanently. The problems started when we got injuries.
"There were gaps all over the team except in defence. The rules state you can only have five loan players in the squad on match day so I made way.
"It ended with me sitting in the stands while the manager did not have enough players to fill the bench!
"Portsmouth were paying me around ?14,000 a week to do nothing. It sounds lovely but it wasn't.
"It just seems as if the rules are holding players back. We would often get different answers from different people at the Premier League and Football League.
"Clubs are confused, managers have no idea and players are stuck in the middle."
Source: Team Talk
Source: Team Talk