thepogg.com has compiled a big report over bonus issues and complaints from players. The short summary of the article is that players are being given bonuses where the cashout limits are ranging from 2 times to 4 times the bonus. This limit or ceiling of how much a player can win really affects the player's ability to win big and the bonus is really not a bonus anymore at this point.

From thepogg article:
These smaller percentage bonuses are actively costing players money. They provide no advantage and act as a tax on players. In our opinion these activities cannot honestly or accurately be described as a bonus. That they’re being added automatically to player accounts without notification or alert and that the terms are giving a misleading representation of the win limit only adds insult to injury.
http://thepogg.com/nektan-when-a-bonus-is-really-a-tax/
The list of casinos that use these terms & conditins
- 7Jackpots
- Bet Reels
- CashReels
- Casino.uk.com
- CasinoMobile.co.uk
- Chomp
- CityAM
- Cloud
- Coin Falls
- EuroViking
- Fika
- Fonesino
- Fortune Frenzy
- Fruity Vegas
- Go Win
- GrandDuke
- GreenDog
- Handy Luck
- Jackpot Jones
- Jackpot Mobile
- Jackpot Strike
- Kerching
- LoveSpins
- LuckyTap
- Mayfair
- MobiReels
- Monster
- mRiches
- Neon Jackpot
- Northern Lights
- PlayUK
- Pocket Vegas
- Pots of Luck
- Pyramid’s Fortune
- ReelVegas
- Sapphire Rooms
- Slot Fruity
- SlotMore
- SmartMobile
- Spin Princess
- StarShine
- The Sun Play
- TinySlots
- Touch Lucky
- Touch Mobile
- VegaZino
- Whirlwind Slots
- WinZino
- XSpins
- Yo
Also from thepogg:
This is a short sighted and greedy policy. The attraction of gambling is that you have the chance to win an exciting amount compared to the balance you’re staking (at least as far as slots games are concerned). This policy looks to remove that possibility. It provides operators an incentive to add as many bonuses as possible, knowing that where a bonus is in play there’s no possibility of having to pay a big win. When bonuses cross the line into disadvantaging player there is an even stronger financial incentive. However the long term implications of this type of policy will be to frustrate and disappoint players resulting in reduced retention levels. They trade long term player loyalty for the short term gain of highly increased chances of smaller profits.