There is no way to tell if a married man is truly attracted to you. It is possible if there is lingering eye contact and a mutual unspoken sensual infatuation that you feel. But just because you feel something that doesn't mean he does. Men are "attracted" to women all the time, from appearance, to smell, to the simple way words may be presented by a female. Even if a married man is physically and or emotionally attracted to a woman, a faithful man with good moral principles and priorities will keep his male instincts in check.
Married men will show their attraction in the same way as other men, although perhaps in a more subdued manner. If a man is interested, he will find excuses to speak to you, compliment you and encourage time spent together.