use strict;

my @swearwords = qw/bad worse ugly/;

my $text='This is a bad sentence with some ugly and worse words';

$text=~s/$_/****/ foreach @swearwords;

print $text;
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works nicely for me, so the error is not in the regex.

Perhaps you should do  while (my $text=$sth->fetch) so you have at least a text to work on!

<Update: Or you could do away with the foreach loop as follows:

use strict;

my $swearwords= join '|', qw/bad worse ugly/;

my $text='This is a bad sentence with some ugly and worse words';

$text=~s/$swearwords/****/g ;

print $text;
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