Sunderland are interested in bringing the 39-year-old back to a club where he is still revered by the supporters, but head coach Lee Johnson has this week warned that no agreement has been reached at this stage.
Defoe is believed to have other offers and at this stage remains keen on continuing his career for at least another six months.
Sunderland are in the market for another striker while Nathan Broadhead continues to recover from a hamstring injury.
Speaking to OLBG, Goodman raised concerns about the possible transfer, but believes the former England striker could be a good signing.
He said: “You don't know what Jermain Defoe you're getting because he's only played two games for Rangers this season so far.
“I think for all parties it would be worth him having a couple of weeks of training and Lee Johnson assessing the situation.”
He added: “If he's got the desire and hunger to play at that level, he certainly has the club in his heart from his previous spell, it's a club that he loves.
“It could be a fairy-tale reunion if they could get him match sharp and I think he would be an asset to anybody.
“I think at the moment, it's the not knowing where he's at from a fitness perspective.
“It's a wait and see job, but if you can get a Jermain Defoe anywhere near the levels of past, then of course anyone would want him.”
Johnson was asked about Sunderland’s interest at his press conference on Wednesday.
When asked directly whether he wanted to bring Defore back to the club, Johnson said that he supported it in principle but that there were a lot of elements to clarify before he could be definitive.
“It’s a difficult question because there’s so many elements that go into that,” Johnson said.
“You’ve got the football side, you’ve got the condition of the player and the gametime, everything has to be looked at in fine detail.
“One of the biggest things is the connection between coach and player as well, and that’s really important.
“So to answer, of course in principle, it sounds like a fantastic idea.
“At the same time, there are so many intricacies that have to be right for all parties to be comfortable and happy with any particular signing.”