The midfielder moved to Vicarage Road in January 2021 and played a key role in helping the club to secure promotion back to the Premier League.
However, for the 32-year-old, things went downhill quickly and he barely featured in the top-flight for the Hornets, who worked their way through three managers.
Xisco Munoz was sacked after seven Premier League games and his replacement Claudio Ranieri lasted only 14 games before Roy Hodgson came in.
Watford eventually finished 19th - 15 points adrift of safety.
Gosling spoke of how he was excluded from first team training for the duration of last term, before hitting out at the club's first team players, many of whom arrived on loan, for not showing the necessary skillset to keep the club in the Premier League.
He told the Watford Observer: "I thought that attitude was a disgrace.
"There were a lot of disgraceful attitudes here last season and that's ultimately the reason we went down. It wasn't a question of ability. Maybe some players didn't always hit the levels they are capable of, but it was the attitude of individuals that did for us.
"They signed [Ozan] Tufan from a Turkish club. He was here on loan: is he going to really care if the club goes down? He knew that whatever happened, he could go back to wherever he came from.
"He'd never played English football at all, never played here, never played in the Premier League. He wasn't bothered and he wasn't that fit either.
"It was a real disgrace, easily the worst dressing room I've ever been a part of. So now that we're clearing the decks and trying to build something new is refreshing."
Gosling also hit out at Claudio Ranieri's time at the club, describing the Italian and his team as being 'miserable' during their four months at the club.
He said: "That time with Ranieri was just really unenjoyable.
"The training we did, the spirit they created, the staff that came with him - the whole thing was just miserable. They were miserable, and it made it miserable.
"I was surprised they lasted four months to be honest. I have been in football a long time, and so have a few boys in the squad, and that time was as bad as it can get.
"If you're going out on the training pitch and just doing five-a-side games day after day, it is literally nothing football. It's kid's football. As a pro, you don't learn anything from it.
"There's a time and place for five-a-sides obviously, but it's usually a few fun games at the end of a session. Doing whole sessions of five-a-side every doesn't win you games. Look at the results on the pitch."
The former Bournemouth ace is now looking forward to a brighter future under new Watford manager Rob Edwards.
Gosling said: "The fresh start is so good. We've signed a couple of hungry players, and I know the hope is that we get a few more