I Am Having Problem With Featured Images In My Website Please Help

I am having a problem with featured images on my website which looks very bad and i donot know hot to fix it
My Website:-
http://www.dealhunterz.com
Just slide over the page and in the left side you’ll see that the images are so dis allocated and the size and pixels are just irritating and it automatically Fixes the image according to size it needs.
I installed many themes and encountered the same problem i.e the theme re sizes the images on its own which looks bad
Please help me with this thing.
Urgent Replies Would be appreciated
Thanks