I do not have much info on the subject, except that the college has coed dorms. Some of the comments that I read have been pretty old. I wonder how parents feel about coed dorms and what feedback they received from their own college kids.
My kids have spent all their college years in coed dorms, as did I during my college days. No issues.
What concerns do you have?
I’m assuming you are referring to dorms where males and females are in the same building but in different bedrooms, as opposed to situations where mixed genders share the same bedroom. In this day age age (as well as for many years), I would think that college dorms segregated by sex are the exception, not the rule.
My D and S17 lived in co-ed dorms. Neither has had any complaints. S17 is currently in a suite with a few other boys. There are female suites down the hall. Occasionally, they hang out in each other’s common areas. S17 isn’t dating anyone and his roommate is gay.
Before my D went away to college, I was terrified by the idea of co-ed dorms. I did not go away for college and dreaded H’s stories about the rampant hookup culture of the 70’s in his dorm. However, kids nowadays don’t seem as promiscuous as we were in the 70’s (at least based on my kids and their friends) and it really wasn’t an issue with my kids.
All of the dorms my kids lived in were coed. It was fine.
I lived in coed dorms back in the 80s. Half the Hall was male and the other half female. Never gave it a second thought.
“I would think that college dorms segregated by sex are the exception,”
This is my impression also. Many universities have one women-only dorm, but most dorms are co-ed. Some are co-ed on a “per room” basis (each room is one or the other), some on a “per floor” basis.
Having different sexes share a single bedroom goes a bit too far IMHO. I have heard of this.
Most dorms are co-ed. Are you asking about co-ed suites? Typically called “gender inclusive”
I lived in both co-ed (rooms all the same gender, but co-ed halls) and single sex dorms in college. I don’t even think there are any single sex dorms at the colleges my kids went to. My personal experience was that the women’s dorms in college were quieter and had nicer common room furniture. There was not less sex in the women’s dorm, though, if that is what you are worried about. We just brought our significant others into the dorm. I never thought twice about my kids living in co-ed dorms. It was fine.
I believe freshmen year S lived on a male floor dorm but the dorm was co-Ed. He only had male room mates. D only had female room mates but didn’t believe her dorm was co-Ed. In any case their apartments were all whatever genders folks chose. D has graduated and lives in a house with her own room with 3 males friends. It works for her and us. S lives alone.
Students seem to care most about the designation of the bathrooms. Suites usually have their own semi-private bathrooms, but traditional shared hall bathrooms can either be single sex or co-ed. Girls in particular are often horrified by the lack of cleanliness when sharing bathrooms with boys. Sometimes the floor votes on how to designate each bathroom in a co-ed dorm.
"Girls in particular are often horrified by the lack of cleanliness when sharing bathrooms with boys. "
I’d argue that is often a non-issue as well. Girls aren’t necessarily cleaner than guys. Being a slob is equal opportunity. Plus, with guys you don’t usually have to deal with long hair left in sinks and showers. 
My college had all coed dorms. Some were single sex by floor, others had coed floors. I was on a female floor my first year and requested coed after that, although I didn’t get it every year.
Personally I always had lots of guy friends and just preferred a mixed group. I also had had lived with guys in most of the places I lived with roommates after college.
My D’s school is the same as mine and she has been on coed floors. Freshman year she was in the honors living community which was coed. This year I think her request was based on the dorm building she wanted. Not sure, as she didn’t ask my permission or advice.
Having shared dorm bathrooms with both males and females, I can say from my experience that some guys are slobs, but so are some females.
For every complaint of beard stubble in the sink, there is one for leg stubble in the shower. 
And that’s just a minor complaint.
In the 80’s I lived in co-ed dorms for 2 years and co-ed wood frame houses (like you’d live in with your family) for 2 years. The bathrooms were single sex in the dorms, shared in the houses. It was fine. No problem. I won’t think twice if my son ends up in co-ed dorms and if I had a daughter, I guarantee I’d feel exactly the same way.
Is there something in particular you’re concerned about?
In the 90s I lived in a coed dorm at GWU. It was coed by room. But we had private bathrooms in each room. No problems.
My DS’s dorm is coed, suite is all male. He thinks nothing of the coed situation, having two younger sisters and a girlfriend at another school. Some suites have bathrooms, others use single-gender floor bathrooms designated by the school. The best thing - all the bathrooms in this building are professionally cleaned. Hall baths - daily, suites - weekly.
I lived in coed dorms all four years. I expect my children will do the same.
My DD has a single in co-ed suite. From her experience the only difference when you have larger presence of males in a suite is dirtier kitchen and bathroom.
Early '70’s saw the start of coed dorms at UW-Madison, a very liberal flagship. I avoided the women’s dorm that had a dining hall in it (open to all) and was isolated from men’s (and other women’s) dorms geographically. The last dorm that was all women finally became coed my son’s freshman year- good timing as there were no returning men to claim rooms, giving him better odds at getting into it. That was several years ago. It may have been old (MY mother lived there once) but has a great location and some of the bigger rooms on campus.
You need to define coed. Sharing a room and/or bathroom is the extreme end. Different floors is different than different wings, or different rooms mixed in.
Perhaps your D is nervous that you will be upset with the common living arrangements at her desired school. Time to discuss with her what the options are and her feelings. This assumes she will be an entering freshman and doesn’t really know what to expect. If she is already at her college and wants to choose a coed dorm- be supportive.
Co-ed dorms normally have separate gender bathrooms, if you’re concerned about that.