Mariner said: "Can I believe it? This may sound a little strange but yes and no.
"The players at this club have been magnificent in every single aspect, professionalism, thirst for knowledge, learning new stuff and putting it into practice. They are joy to work with."
Mariner admitted scoring four at Home Park was a good way to end a goal drought that has seen them score once in six games before Monday's win.
The former England striker added: "There's nobody on the planet that can tell you how it comes about. You go through barren spells, dry spells, and all you can do is keep working and the players have been terrific and they got some just desserts today."
Plymouth opened the scoring in the 13th minute following an exquisite through ball from left-sided midfielder Chris Clark into the path of striker Jamie Mackie on the left side of the penalty area.
Mackie took the ball in his stride but was felled by marker and Royals skipper Ivar Ingimarsson.
There were no complaints from the Reading players and Plymouth playmaker Alan Judge duly despatched his third successful penalty of the season.
But the match exploded into life on the hour when there were three goals in as many minutes.
Judge's corner from the right was headed home by Argyle's unmarked Icelandic international central defender Kari Arnason at the far post.
Reading responded within a minute after Luke Summerfield cleared substitute Grzegorz Rasiak's effort off the line in a goalmouth scramble. Jobi McAnuff crossed the ball in from the right and Gylfi Sigurdsson powered in a header to make it 2-1.
In the next attack, Argyle restored their two-goal advantage as Mackie teed up Clark down the left.
His cross was converted by Judge's powerful header after he had beaten keeper Adam Federici to ball the at the near post.
Argyle - who had not scored in five matches before their win at Cardiff - were not finished and when Federici failed to hold Mackie's 84th-minute strike, substitute Ashley Barnes pounced for his first goal of the season.
Reading caretaker boss Brian McDermott admitted: "I didn't see it coming. We had a really bad day, really disappointing.
"If you come to a place like this and don't win your individual battles that's what can happen to you and that's what happened to us today.
"The fact they have out-fought us hurts more than anything. I don't know where that has come from. I didn't expect that.
"From the start I didn't think there was anything in the game and then we gave the penalty away.
"We got ourselves back into the game at 2-1 and have then given another poor goal away.
"All we can do now is look forward to the next game - and that's against Liverpool (in the FA Cup) - and it's a massive game."