What is a Fortunate Word™?

Question

_{In the spirit of the What is a Word™/Phrase™ series started by JLee, a special brand of Phrase™ and Word™ puzzles.}

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If a word conforms to a special rule, I call it a Fortunate Word™.
Use the following examples below to find the rule.

$$ % set Title text. (spaces around the text ARE important; do not remove.) % increase Pad value only if your entries are longer than the title bar. % \def\Pad{\P{0.0}} \def\Title{\textbf{ Fortunate }} % \def\S#1#2{\Space{#1}{20px}{#2px}}\def\P#1{\V{#1em}}\def\V#1{\S{#1}{9}} \def\T{\Title\textbf{Words}^{\;\!™}\Pad}\def\NT{\Pad\textbf{Not}\T\ }\displaystyle \smash{\lower{29px}\bbox[yellow]{\phantom{\rlap{rubio.2019.05.15}\S{6px}{0} \begin{array}{cc}\Pad\T&\NT\\\end{array}}}}\atop\def\V#1{\S{#1}{5}} \begin{array}{|c|c|}\hline\Pad\T&\NT\\\hline % \text{ MY }&\text{ OUR }\\ \hline \text{ NOW }&\text{ AGO }\\ \hline \text{ CAR }&\text{ OIL }\\ \hline \text{ SINK }&\text{ SAIL }\\ \hline \text{ REAL }&\text{ HOAX }\\ \hline \text{ NUTTY }&\text{ CHEWY }\\ \hline \text{ SHEEP }&\text{ GOATS }\\ \hline \text{ BLAME }&\text{ ACCUSE }\\ \hline \text{ EIGHTH }&\text{ FOURTH }\\ \hline \text{ GLANCE }&\text{ VISION }\\ \hline \text{ YELLOW }&\text{ ORANGE }\\ \hline \text{ PARCEL }&\text{ PACKAGE }\\ \hline \text{ PROTECT }&\text{ ASSAULT }\\ \hline \text{ CLUSTER }&\text{ COMPLEX }\\ \hline \text{ DECREASE }&\text{ INCREASE }\\ \hline \text{ EXERCISE }&\text{ FEEDBACK }\\ \hline \text{ TREATMENT }&\text{ OPERATION }\\ \hline \text{ PRINCIPLE }&\text{ PRINCIPAL }\\ \hline \text{ REPEATEDLY }&\text{ CONTINUOUS }\\ \hline \text{ CENTERFOLDS* }&\text{ SUPERMODELS }\\ \hline \text{ ENTREPRENEUR }&\text{ PROFESSIONAL }\\ \hline \text{ DISTRESSINGLY* }&\text{ UNFORTUNATELY }\\ \hline \end{array}$$                                         * These are Very Fortunate Words™

 

And, if you want to analyze, here is a CSV version:

Fortunate Words™,Not Fortunate Words™
MY,OUR
NOW,AGO
CAR,OIL
SINK,SAIL
REAL,HOAX
NUTTY,CHEWY
SHEEP,GOATS
BLAME,ACCUSE
EIGHTH,FOURTH
GLANCE,VISION
YELLOW,ORANGE
PARCEL,PACKAGE
PROTECT,ASSAULT
CLUSTER,COMPLEX
DECREASE,INCREASE
EXERCISE,FEEDBACK
TREATMENT,OPERATION
PRINCIPLE,PRINCIPAL
REPEATEDLY,CONTINUOUS
CENTERFOLDS*,SUPERMODELS
ENTREPRENEUR,PROFESSIONAL
DISTRESSINGLY*,UNFORTUNATELY

The puzzle satisfies the series' inbuilt assumption, that each word can be tested for whether it is a Fortunate Word™ without relying on the other words.
These are not the only examples of Fortunate Words™; many more exist.

What is the special rule these words conform to?

$ $  

Hints

helpfulness level 0:

At ten letters, TREMBLINGS is the shortest a Very Fortunate Word™ can possibly be.

helpfulness level 1:

Prior to October 1988, no Fortunate Words™ existed as such.

Answer 1

A Fortunate Word is

a word that can be formed during the bonus round of Wheel of Fortune. The letters R, S, T, L, N, and E are always provided; the contestant can then choose 3 more consonants and a vowel.

Not Fortunate Words

Have at least 2 different vowels that aren't E, or at least four different consonants that aren't RSTNLE, and thus cannot be formed this way.

Very Fortunate words

use all 10 selected letters. Thus, the shortest Very Fortunate word has exactly 10 distinct letters, e.g. TREMBLINGS.

October 1988

was when the rules of the bonus round were changed to their current format.