Am I sinful if I work for a company that imports household goods and supplies merchandise like glasses to hotels that serve drinks to tourists?

If the cups are specifically made for drinking alcohol, or if you know that the hotels buying them use them for serving alcoholic beverages, then it is not permissible to sell them, because it constitutes aiding in sin. However, if they are originally used for a permissible purpose and are not designated for drinking intoxicants, and you do not know that the hotels use them for serving alcoholic beverages, then it is permissible to deliver them to hotels.