Yes, if it is possible, I have done so and will do so again.
>> Or have you found out your competitors registering on yours as customer to check out your features?
Yes. This is a common practice with any company that has competition.
I don't see how it's different than Apple buying up Androids or vice versa. Blindness doesn't help your business nor does it help your industry as a whole.
>> Would you use a real name?
No.
>> Is it immoral?
Morality is relative. If you have personal objections to doing this, that is one thing, but when you consider that:
a) everyone is spying on everyone
b) you are looking out for a company interest and not your own
... your personal ethics should be separated from the work you do, within reason.
It would be immoral if you managed to log in and sabotage their business. For example, you can place an order of 1,000 widgets and then "change your mind" a week later after the company, in good faith, placed the product on hold, preventing them from filling the order with a legitimate customer. Seeing what your competition does, signing up for mailing lists, or ordering a product catalog, or similar non-destructive behavior is fine in my book.
With my current project, we've learned about every product out there that even touches on a portion of what it is that we're trying to do. We have and will continue to learn the competition. If the existence of a feature is a competitor's entire advantage, then they either will have IP protection or they'll be out of business soon.
Use the site according to their TOS and use your real name. If you aren't abusing their service, there's nothing to fear.
Information on the web is public. I see nothing immoral about using information that your grandma could find.
It is a regular practice for all companies, as it should be.
I don't think it should matter if I use my real name or not honestly. I am becoming a user to get an idea of the space. I think that is a completely reasonable thing to do, and besides, if the company is searching their users for their competition then I think that they are not spending enough time on their product and more on trying to stop their competition.
It is by no means immoral, you are doing research on the space you are in by looking at the publicly available products out there. Now if you were somehow getting access to internal documents or development releases of the product then I would say yes that is immoral but looking at a competition's available product is perfectly fine in my opinion.
Now a couple points I'd like to bring up about this is that a) you should not be doing things such as writing negative reviews of the product b) you shouldn't be using the product to make other users' experience with the product negative c) Use the information gained to get an idea of what is out there, what users like about the product, and how your product is similar and different. Not as a new feature list.
The paper at this link has some good information about issues and attitudes around competitive intelligence - http://osint.pbworks.com/f/Trevino.pdf
Also, there is a Society of Strategic and Competitive Intelligence Professionals (like, who knew that was a thing). Their code of ethics is here - http://www.scip.org/About/content.cfm?ItemNumber=578
Unnecessarily placing orders leading them to believe you are a genuine is customer would be immoral though.
I had a hilarious incident when a new user signed-up & responded to my welcome mail saying, she is part of a stealth startup & needs guidance with choosing payment gateways. Silly part was her rapportive profile clearly showed her linkedin profile, that she joined competitor as product manager just a few months back. We had a hearty laugh & let it go.
I often get sales calls from them, and explain to the sales guy. They usually get a laugh. More-so when I was a CTO.
I don't think it's any different than that.