Sentence:  Usually she marked the few who did thank you , you did n't get that kind much in a place like this : and she played a little game with herself , <WSD>seeing</WSD> how downright rude she could act to the others , before they 'd take offense , threaten to call the manager . 
Meaning of the word marked with <WSD> tags:  find out, learn, or determine with certainty, usually by making an inquiry or other effort