As I shift many URL's on my site from non-friendly to friendly, I came across an old URL that was used for testing that google later ended up scanning but now I no longer use the URL. Its in the unfriendly form like this:
In the past, that URL matched another on my site and in order to rectify it, I had to change the status code (and make the URL not return an actual webpage). At first I thought using the code 410 to indicate gone to google, but now I figured http status 400 is better because all my other "clean" URLs never contain an
& in them and http status 400 stands for malformed request.
Is this an acceptable practice? or should I just convert it to http status 410? What would search engines think of this practice? (I'm just trying to follow standards here)