Once bitten, twice shy.
Is this a legitimate saying in Portuguese? In English scald refers to a reaction with hot water, and my Portuguese dictionary also defines escaldar as a reaction to hot water. Escaldar - Dicio, Dicionário Online de Português
Indeed, that definitely looks strange, so I checked on Tatoeba and Portuguese Wiktionary, and this is what I found : -
There is a Portuguese Wiktionary entry for a slightly different version, but where I understand the meaning to be quite different - gato escaldado tem medo de água fria.
The sentence also shows up on Tatoeba in these two forms -
Now, if I had seen sentence 1 then that would make sense to me as an idiom.
If I had seen sentence 2, then I could probably make sense of that as an idiom with a strange (maybe poetic?) word order - i.e. it works for me if I read it in a Yoda voice (or should I say - 
“it for me works, if it in a Yoda voice I read” 
).
However, the sentence in this case here just looks confusing to me. If you insert a comma between escaldado and de then you get sentence number 2 that I referenced from Tatoeba, however as it is currently written without the comma … that just looks odd.
P.S. I also like the alternative that they have on the Portuguese Wiktionary page, cachorro mordido de cobra tem medo de linguiça - “a dog bitten by a snake is scared of sausages” 
.
Once bitten, twice shy.
Thank you zzcguns. I think that your sentence #1 is probably the idiom. As an idiom is still seems confusing and the translation to once bitten twice shy is a bit sketchy especially in a language lesson. I think it may be better to translate a idiom into straightforward language. With sentence #1 that might be the cat (or person) generalizes fears acquired from past experience.