Just my humble opinion...I think it's great to do a little bit of research on a prospect before calling or seeing them. It gives you some ammo before you speak/meet with them and in sales, sometimes you need some extra ammunition. 

Plus, I believe your prospect is impressed you did some research. It shows you care about their business, their wants and needs and you can now provide your product(s) or service(s). No one wants to be "sold."  

I can give you one example of a closed sale from this. I met with a potential customer. When we met, he told me he was not going to buy a newspaper ad from me, and he told me right away, the answer is NO! 

Before our meeting, I saw my prospect was advertising in a competitor's newspaper. I showed him the ad and said you've got this area covered, but we have a couple newspapers in the county, which this newspaper doesn't cover. I asked him how much he was paying for his ad weekly. When he told me, I mentioned to keep advertising with this paper, but in addition, advertise with us. We can put that same ad in the other two areas they service (the two most affluent areas in the county) for the price he's paying with the other newspaper. He gave me his business right then and there.