I rarely (never) ask permission to reblog something because;

1. It’s Tumblr; nearly everything I come across was reblogged from someone else x 10,000.
2. I’m way too lazy busy to do that every time.
3. Most people post someone else’s art, quote, photo, and so on, and therefore have no real ownership over it.

However, if I did reblog something you actually do have ownership over and you didn’t want it out on the internets; just let me know. 

If I reblogged you and added one of my wonted charming quips, which you didn’t find very funny; let me know! 

If it really bothers you I’ll likely be happy to remove it.

I actually don’t want anyone’s feelings to be hurt, and I certainly don’t want anyone to feel laughed at. That’s just about impossible on the internet, but I’ll give it a go.