What does the statement “Once I did bad and that I heard ever. Twice I did good and that I heard never” mean?

Question

What does the statement

Once I did bad and that I heard ever. Twice I did good and that I heard never.

mean? In what situations is it meaningful?

Answer 1

It means that if you do a bad thing, people will remind you about it forever. But if you do a good thing, or many good things, often people won't bother to comment on it.

Answer 2

I think that this sentence means that the bad thing that the person did were highlighted many times while the good things that the person did were never highlighted.

It is ordered to make the statement rhyme.

Once, I did bad,
and that I heard ever.
Twice I did good,
and that I heard never.

Answer 3

It's a modernised version of what was described as an "old saying" back in 1753...

Twice I did well, and that I heard never; Once I did ill, and that I heard ever

Personally I don't much like the "bad" version. I see "bad" as an adjective ("I did bad [deeds]"), whereas "I did good" seems more adverbial (good=well). I know in principle I could read both good/bad as adjectives - but in practice I don't, so the juxtaposition doesn't quite work for me.

There's the (relatively recent, I think) usage of "bad" as a noun meaning "mistake", but I always think one needs to be careful with this - it's very informal, and can easily appear uneducated.

I'm not sure anyone uses "bad" as an adverb in normal speech, but in OP's example it seems to adverbially modify "did/to do" (where we'd expect "badly", but that doesn't fit the "rhythm" of the couplet). On the other hand, the original "ill" is a perfectly valid noun, adjective, and adjective (though once common, ✳illy✳ is no longer an acceptable adverb since ill itself acts as an adverb).

In common parlance, the statement "Once I did X", usually means "I used to do X" (quite possibly very often). OP's "modernised" version is therefore something of a garden path sentence, in that we have to re-evaluate that first word (definitely by the time we get to "twice", if not before).

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As to meaning, it's just another cynical observation on life in general, along the lines of...

Laugh, and the world laughs with you; Weep, and you weep alone. (no-one likes a loser).

Bad news travels fast (good news travels slower, hence "No news is good news").

The evil that men do lives after them; The good is oft interred with their bones. (pace StoneyB above).

TL;DR: OP's saying just means that people are more likely to remember and talk about your single past mistake than your many past successes.