I volunteer at a rescue and I really enjoy it. The owners are nice, knowledgeable and appreciative of my help, same with the trainers/barn managers. It’s far from perfect, which also makes it hard at times because I do think they have too many horses which means that some horses get very little turnout and a lot of the younger horses there need a lot more consistent work than we can give them to make them into good adoptable prospects - the vast majority of horses there get a ton of turn out and lots of hay and grain when needed and the horses are in generally good condition. So it’s definitely not all sunshine and roses there, and even if it were, sometimes it is still hard because there are sick and/or old horses that have to be put down.
On the other hand, a friend was working at a different rescue, much smaller scale but with the intention of rehabbing horses and getting them in to competitions and showing off what they can do (they do have some happily retired horses who couldn’t be rehabbed enough to ride). Very nice facility, very good care, everything is top notch except the owner is pretty much the worst stereotype of a horse person who bad mouths everyone, starts unnecessary drama and yells when you don’t read their mind. My friend stayed as long as she did for the horses but ultimately left because the owner got to be too much for her.
So basically rescues can be a lot like any other horse endeavor, some are good but could be better, some are great but the people leave a lot to be desired, and then there are also some in my area that claim to be rescues but are glorified hoarding situations. So if you do volunteer with a rescue, go in with your eyes open and make sure it’s a good one.