hehe, i think i'll quote downtownamber on this one, something she said in the chat a few days ago: "there's being a sadist...and then there's being a bastard" [or something along those lines, sorry if i'm effing up the quote].
This is so true, humour or no humour. I think we can exclude you from the second category, Mr. 'Nice Guy'! *grins*
To be honest I'm glad you brought this up, partly because it's nice knowing that I'm not the only one worrying, all the replies were very well worth reading and gave me things to think about which had only briefly crossed my mind and then just fluttered away.
I seriously doubt my ability to add something as good, long or well written as previous replies, but hey, i'll add my small thoughts on it:

Some things you just know about yourself, some things you discover in due time and some things will remain hidden in the depths of your inner psych for years to come. I'm guessing you know you're not a bad person, maybe a tiny bit perverted but we welcome you wholeheartedly to the club and enjoy having you here, you'll discover further wants and needs in the future and, through discussion and relationships the rest will probably come to you.
Us subbies aren't the only ones with limits--or so I'm told *grins*--so your kind as well is always on the lookout for warning signs for when things are going too far, too fast, too creepy! Gut feelings are good, trust them, i like the saying 'better be safe than sorry'.
I do wish you the best of luck and i will be keeping track of this discussion, it's really interesting and thanks again for bringing it up!