I would like to check this online translation, too, amabo te (vos?)
Proposed (mis)translation Each miserable (man) was saying: “I am a Roman citizen.”
I don’t like that because it sounds like “every unhappy person used to say…,”
Shouldn’t it be something like: “Any lowlife used to claim to be a Roman citizen.” That might be too informal but it’s the right idea, isn’t it?
Without any context the tone (colour) that one should use is difficult to assess.
This is a quotation form Cicero From the Second of the Verrines which in its original context is:
“Cervices in carcere frangebantur indignissime civium Romanorum, ut iam illa vox et imploratio “Civis Romanus sum,” qua saepe multis in ultimis terris opem inter barbaros et salutem tulit, ea mortem illis acerbiorem et supplicium maturius ferret.” (actio 2, book 5, section 147)
(There, in that prison, guiltless Roman citizens were most shamefully strangled. Now at last the cry “I am a Roman citizen,” the famous appeal that has so often brought men help and rescue among savage races in the furthest corners of the earth, was to hasten the infliction and increase the agony of these men’s death. Loeb)
As you will see Cicero’s meaning is the opposite of what you were proposing. Far from disreputable men claiming (falsely) to be Roman Citizens it was reputable men invoking a claim which should have given them protection against the avarice and cruelty of Verres.
Context is indeed everything! 
Okay, thanks, I had no idea of the context.
How many translators does it take to screw in a light bulb?
1 - It depends on the context.
2 - It’s hard to see how they could get inside one in the first place.
“Unhappy person” seems very unlikely for reasonable contexts. Miser makes me think “wretch” before “lowlife” though.
Now that Seneca showed me the context, I agree. The idea of “lowlife” was that I thought the context might be “before traitors had to forfeit their rights of citizenship, any lowlife (unprincipled traitor) could invoke his Roman citizenship as a defense” , probbly because I had recently read something on that subject in Cicero.