If that's the case, you should already have a written list of things you're looking for in a house, and things that you definitely don't want. You might, for instance, need 3 bedrooms and 2 baths. You might need another room, somewhere, for an office. If you have a dog, maybe you want a large yard that can be fenced in, if it isn't already.
So, put together a checklist. Include all the house basics on it, plus your list of "must haves" and "must not haves." As you go through the house, fill out your checklist. That'll help keep things straight. It'll also make sure that you don't overlook something important to you, then later try to remember whether the house had it or not.
Next, and the checklist will help keep you focused, don't be distracted by minutia. And that minutia can be positive or negative. If the home is staged, for instance, great. It can let you see what you can do to/with the house. But remember, you're not buying that cute antique sewing machine set up in the bedroom. You're not buying that bowl of fruit on the dining room table. And, on the other hand, if a house hasn't been staged, don't get distracted by the photos of 3 generations of the family on the walls. Or the odd artwork. Or even the pet smells. All those are temporary and fixable.
Pay attention to the neighborhood. Both the immediate neighbors and the conditions within a several block radius. Make sure you're comfortable with that.
You can ask the agent questions and, if you're really lucky, you may get some useful answers. But often, the agent at the open house isn't the listing agent, and often doesn't know much about the listing. And if the agent does know, he/she is representing his/her client, and may choose not to answer. For instance, you might want to figure out how motivated the seller is. So you might ask, "Why is the seller selling this property?" Useful answers are: "They're moving because of a job relocation." Or "They've already bought another house, so they're selling this one." Or "The owner was elderly, and moved in with her children." Less useful answers are: "Oh, they just felt it was time to sell." Or, "I really don't know."
Try not to let an unhelpful agent discourage you. Now, I'm a Realtor, and there are many, many excellent Realtors. But not all of them will be at all the open houses you visit. I've run into innumerable agents (men), especially during football season, with the portable TV blaring away in the kitchen, and they can't be torn away from it to help customers. I've run into many other agents (two agents, sometimes two women, sometimes a man and a woman) so engaged in talking with each other that they don't even notice you. I've run into agents who are midway through their favorite author's novel and can't put that page-turner down. I've run into agents who insist the house is absolutely great, despite its flaws or drawbacks, and seem to believe it. Now, I've also run into some great agents, and they outnumber the poor ones. But, if you happen to encounter a poor one, don't let that interfere with your evaluation of the house.
Those are just a few suggestions. Hope that helps.
This might depend upon what your goals are upon visitng the open house. Some visitors are interviewing and scouting for listing agents. Other visitors are looking for a buyer agent. Others are looking for general info for a future purpose. Still others are actively and aggressivley searching for a property now.
Since having a great agent on your side as either a seller or buyer, I aways suggest that you ask questions about both that property and the market to determine an agent's command of the market and ability to share that info w/ prospective clients. Ask questions about how this property compares to other properties in the area; how many properties in the same price range or style are available in the immediate area, what the average DOM are for that area, what the average list to sales price is for that area. Also ask questions about that property........what type of heat? how old is the roof? what kind of roof? Is this agent knowledgeable about the property they are representing.
good luck w/ your open house visits.