I recently purchased traffic via a solo ad and had very, very poor results. Everything went normal up until the payment was made. Then communication with the seller changed, I saw traffic going to my page but also saw very very few opt ins.
Prior to running that solo I put my free traffic generation on pause for a few days and waited until I saw little to no traffic to that particular page ( it is a very new capture page). When questioning the seller, I was lucky to get a response and when I did it was vague. This has only happened to me 2 times with purchasing a solo ad (maybe it was the page, maybe it was the swipe (since he wouldn’t show me what he sent I guess I’ll never know)
Now for free traffic. I like to use safelist traffic for certain offers, sure safelist traffic can be a pain to use but there is some value to it. It takes some time clicking to get credits but then you get to test your swipes on the traffic. If you can get a few opt ins on your lander using safelists, I would say your swipe and landing page cannot be that bad.
The ups of using free traffic, well first it is free. The quality may not be the same but there are no guarantees with any traffic source. You can also find loads of free traffic sources. There are safelists, seo, back linking strategies, etc.. You can also build your own free traffic using link circles, social media and videos and such.
The major downsides (in my opinion) of free traffic is the time it takes and the quality of the traffic. Until the seo and link circle traffic kicks in. The downside of seo and linking strategies is that other sites may be in control of the link. They can remove it without notice and can “nofollow” it without notice. Thus requiring you to be checking regularly. The struggle with seo is that it is a constantly changing game. Also what works with one search engine may not work with others..
The ups of paid traffic. You will normally get all the traffic you have paid for. If you have the budget, traffic is easy to find. The downsides of paid traffic (again only my opinion) is you have to believe the seller or the sellers reviews on the traffic niche and quality. There are a couple of ways around this.
You can purchase your traffic through a reputable traffic network or search engine. Example bing ads, or adwords, or a system like adengage or mlmleads. Then there are solo ads. You can scour fb solo ad group and find a seller and check reviews and message back and forth and then decide if you trust the seller and his proposed product and make a purchase. This route can be difficult. I have done this a couple of times and have had 50/50 results. Some were good and a couple were absolutely horrible. (see top paragragh again for possible reasons).
There are also solo ad vendor networks that can be used. I personally have had better results using this avenue. Check out solo checker (cheaper maybe) just be sure to message seller and make sure they are still active and maybe ask them about your offer. There is also Udimi. This one is good and very active with sellers. The rating system is good and the traffic usually is also.
I hope you were able to take something of value from this rambling, when it comes to traffic for your site(s) you will need to constantly be testing and watching or spending. I know of ppl how rely on udimi sellers and also know of people who rely on only buying clicks from networks and they are making nice money online. If you have questions please feel free to comment or email me.