I found out by accident some time ago that you can load full size images to Photobucket to display in a forum post rather than scaling it yourself
Photobucket will scale to produce two versions. The largest can have a long dimension of 1200 or so pixels and a smaller image 4-500 pixels. The smaller is shown on the forum page and if you click on it you will get to see the larger image.
With less compression the larger image is much easier to make a judgement on.
You can also right click on the forum image to get the option to copy the image, you actually get the larger image and can paste it into your editing program if you want to play with it.
Probably most old hands know but I can't recall seeing it mentioned anywhere