Myrtle didn't advertise her services, there was no external evidence of her business, and neighbors weren't inconvenienced. If you're taken to court, you have two main lines of defense. The first is that your neighbors or the condo association are misinterpreting the restrictions and that your business use is allowable. Second, if the neighbors did not object to prior business uses, they have, in legal effect, waived the right to do so now. In other words, their inaction in the past has nullified the restrictions.
Judges are often sympathetic to homeowners seeking to enjoy the use of their property.
If neighbors have been lax or the restriction is vague, you have a good chance of getting a favorable ruling if your business use doesn't really hurt your neighbors or change the residential character of your neighborhood. On the other hand, if the legal restrictions are tightly drafted and your neighbors acted swiftly to enforce them whenever a violation came to their attention, even a sympathetic judge won't be able to help you. But slugging it out in court should be a last resort. If you're both dogged and diplomatic, you may be able to find a way to operate your home-based business. Look first at the rule to see how restrictive it is.