I do it all the time if I'm typing too fast or basically just not concentrating enough. Usually I mix letters (eg, tiegr instead of tiger), but fortunately I tend to either notice when scanning through or if its a photo title I send a surreptitious pm to a moderator to correct it before anyone notices
there was a period where there was a time limit for editing photo titles, due to Sim rearranging how the galleries worked, which has now been corrected. But in the case of my post, I actually meant to write "thread titles", which can't be edited by oneself (see, that was another one of those mistakes I make when posting too fast! )