UPDATE: added some code, i apologize in advance for the sorry-@$$ regexes within, I'm still learning

I suggest splitting the text file up by sentences and x-ing out anything that is first letter capitalized and not at the start of a sentence. But then again, I don't know what kind of text file you are looking at. If there are any more specific requirements post them.
this is an extremely simplified example of what I mean: 

$paragraph = "This is a group of words. It mentions people like Joe Sm
+ith and Jill Doe who work at Aerodyne Laboratories, INC. The facility
+ is located in Springfield, MA and is famous for it's llamas, lizards
+ and Gork the giant robot.";

@text = split(/\.[\s]*/,$paragraph);

foreach $line(@text){
$line = lcfirst($line);
$line =~ s/[A-Z][a-z]+/XXXXX/g;
$line = ucfirst($line);
}
print join ". ", @text;

[download]

produces:
This is a group of words. It mentions people like XXXXX XXXXX and XXXX
+X XXXXX who work at XXXXX XXXXX, INC. The facility is located in XXXX
+X, MA and is famous for it's llamas, lizards and XXXXX the giant robo
+t.

[download]

In reply to Re: Perl spell checker by thunders
in thread Perl spell checker by Anonymous Monk

Title:
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