Does the company have a written corporate policy on sexism? It should have and it should express a zero tolerance attitude. Does the company actively support womens groups through funding and promotion of meetings and activities such as lunch and learns with outside guest speakers. What corporate executives (women and men) are members of such groups and who is the executive officer that acts as sponsor?
When you interview observe the diversity , or lack thereof, in the people you meet and see in the halls and office spaces. Your eyes won't lie. Does the company have a chief diversity officer? Has the company won any recognition awards for diversity? Are there any wall plaques in the lobby proclaiming the companies pride in winning such awards?
What is the gender mix of interviewers? Of management? Of executive officers? Of the board? Does the annual report address its activities to promote diversity? Google the internet with keywords of the company name, diversity, sexism. What results do you get? Discrimination suits or awards? Google the corporate officer and board member names. My CEO's name returns diversity awards.
When a women interviews you ask her about opportunities for women in the organization. Ask for examples. Ask her to tell you about her career in the company. Ask for a candid observation on how the organization treats women. Is the response one positive enthusiasm or short answer of indifference (or embarrassment)?
Usually one or two companies will clearly stand above all others in the quality and depth of people you interview with. It will be obvious, not subtle differences.
I wish you well in the organizations you work for in the future. Strive for what you believe is right, but don't waste too much time with the wrong company. If you find you spend time complaining about the company then you know it's time to move on. Make your personal goal to become the kind of person you would be proud to work for.