And Roddenberry suggested that Troi have three breasts.
Until Marina Sirtis was instructed to come up with a Betazoid accent, there were plans to develop a relatively simply alien latex application for her character. Hence Gropler Zorn's "You have brought a Betazoid to this meeting" scripted complaint. The writers were assuming an alien look would be present. Surely, just having black irises would not be such a sudden, significant indication to Zorn - unless he could also sense Troi's empathic powers?