Spiller is part of a 30-strong ethical adviser co-op that has released guidance as part of ethical investment week.
The co-op offers ratings on funds to help investors decide how ethical they are.
He said most fund managers were now describing themselves as ethical managers and talking about how much they take account of environmental, social and governance factors.
"You have to be able to differentiate between the different claims that are out there and a real concern for the regulator is the jargon that gets used - it is not clearly explained and defined.
"In essence, there is a lack of real depth and education to enable an investor to understand just to what extent is this particular fund manager committed to ethical investment and walking the talk as opposed to it being a PR glossy brochure spin exercise."
Spiller said there was also plenty of research showing that investors could make money while also doing good.
"I was flying the flag relatively solo in the early days and it's been great to see more and more people coming on board with this. But nowadays those questions really need to be challenged and put aside because we have so much evidence that it is possible to do well and do good."
Spiller said ethical investment had also evolved a lot since 2016 when KiwiSaver funds ditched nuclear and weapons investments en masse after the controversial investments were highlighted by media.
"It's moved pretty dramatically. Now there's an increasing focus on what you are doing from a positive impact point of view."
He said it was not just about avoiding the bad but creating the good.
"For an investor, there's a much richer range of choices and much more depth available, and companies are being challenged to meet the expectations of global best practice.
"And I think many New Zealand companies are keen to do that. The whole conversation has shifted from harm avoidance to positive impact and how can I really do some good with my money rather than just what can I do to be relatively neutral."
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