In real life I have had several roles -son, manager, student, brother, lecturer, employee, nephew, uncle, counsellor, lover, dominant, submissive, cousin, partner, grandson... In Second Life the range of possibilities is even greater - even down to being able to change gender and species.
One of the easiest ways to experience a full range of possibilities is by using an alt account. Yes, I know people frown upon alts and there is always someone there to say "well I have only ever had this account" and "I hate alts". In my opinion it depends what you use them for. I have had several alts over my time in SL. I don't use them to trick to people; I don't use them to create drama; I don't use them for malicious purposes.
Some people know me as one person, others know me as someone else...there are quite a few people who know a couple of me, and they know it is me. One of the main things I use alts is for is to role play. I can be a man or a woman, a master or a slave. I have been all of those. Before anyone starts jumping up and down, I don't get in to serious relationships with people and I certainly don't do it in a female avatar.
I read something on a forum once where straight guys in Gor insisted on photos and voice chat before they took a woman 'to their furs' so they were sure they were getting a real woman. That's is all very well but photos can be fakes and voice changers, such as that built in to the new viewer, can make you seem totally different. To be honest, I could pass as a woman on voice without the need for such tricks. I go to Gor for role play not for pixelated porn. Sex is quite an integral part of the Gorean lifestyle and I know for a fact that some of the male avatars I have been with have women behind them. Does it honestly matter? If you think that a pixel poking is going to 'queer you up', you have deeper issues and should address your concerns about your own sexuality before continuing.
There is more to being an alt; I love the anonymity. I have a large SL family, I have friends both in and out of role play situations. Sometimes it is great to slip in to another avatar and just go exploring, visit a club I would not usually go to and have some time to myself with TP requests and IMs hitting me every few minutes.
So from my perspective, there is nothing wrong with being an alt...so long as you don't mess with people's emotions or use your altness to manipulate people or events.