Pay for comment is good strategy so for example if you are advertising on any platform you may get guest and a guest is in half case a spammer that is labelling advertisement that has no relation to the topic of the blog means may be advertising an affiliate link in sports news of a PTC site that has no relation with subject however pay a reward for comment may have good comments and interaction and if you find many people comment right way then even visitor from organic traffic will be couraged to comment and this may increase blog sales for place rental by place adscence ad like propeller ads or rental script like linkslot.I am not sure if this is a good method, but I see people using webmaster forums for blog promotion. They give incentives to the people to visit the blog and leave comments. I think as long as you are not asking people to click on ads, you are good to go with this kind of promotion method. Or maybe you could try influencer marketing.