For me there is no problem with somebody criticising my blogs, I do on the other hand have a problem with people who make it personal and insist on insulting the blogger for writing what he or she did. I leave comments that criticise my blog even if in that same comment they might also sneer at me and my supposed prejudice or ignorance. As long as there is something in it that relates to the blog and isn't just about how stupid I am for writing the blog I will accept the comment. There are unfortunately also many people whose only purpose is to insult the writer in whatever way they can, most of these people will also do it anonymously.
I don't see the use of having to insult the blogger for his or her opinions, even if they seem distasteful to me or I don't agree with the description at all. You don't need to insult somebody to make a point, you can argue with a person without having to insult the person. Insulting somebody else doesn't make you right or your point any stronger, it just shows your own weakness.
There is another thing, blog are not written for the general public, they are written for friends and family. They are not written to convince us of that person's view, but to relate to those friends and family back home what the blogger is experiencing. There might be bloggers who really hate the place they have been to, hate the people, feel themselves and their own culture superior to the one they are writing about and it will result in an offensive blog for us, but it wasn't meant for us. It might be sad for the friends and family because they will get a very skewed image, then again maybe they have the same convictions anyway and if they don't, they have the option of commenting on the blog. I think many people don't know or don't realise that their blog is available for everybody to see. I don't agree with the tenants of National Socialism, so I would never go to a meeting of neo Nazi's. If I happened, by accident, to walk in on one of their meetings I would leave because I know I would get highly excited, insulted, angry, physically sick and generally depressed by the fact that there are still people who do actually agree with Nazism. Alternatively I would, if possible, try to convince them of their wrong without criticising their intelligence but focussing on the subject. The same is with a blog, if I would happen to find a blog that I find repulsive, I would either close it or if I really felt strongly about it, leave a comment about the blog, but not the person.
The point is, a travel blog is not an opinion piece in a newspaper, it is a blog meant for a specific group of people written by somebody with certain ideas, opinions, feelings and upbringing which will relate in the way it is written and the views expressed by that person. Those for who the blog is written will know the person and will know about his ideas, opinions and all that, so they will get what they expect to a certain extent. A blog doesn't have to be true, honest, unbiased, tasteful, respectful, educational or anything. This is not the BBC (and even they are not totally unbiased, that would also be impossible, but they will try at least). If you want an honest account of a country it is best to look at very many different sources, a blog might be one of the sources, but it certainly shouldn't be taken for anything more than it is.