You see, her widow's garments would have identified her to the outside world as a widow. But she took them off from her, ...
Judah thought she was a harlot because of the way she was dressed. That is why it specifically said she took off her normal clothing. Now what was in her heart? She wanted a husband that was promised to her, and the way she decided to get it was to seduce Judah, and so she seduced him using clothing. That must have been, for the times anyway, pretty revealing, because he fell right into the trap.
